Correctly load guile extensions from /usr/lib or /usr/lib/[amd64,sparcv9]
depending upon whether we are running the 32-bit or 64-bit version of guile.

Changes taken from the guile version 2.X source code and wedged back into
the legacy guile version 1.8.X that we have in Userland/Solaris.

--- guile-1.8.8/libguile/Makefile.in.orig	2016-05-27 06:40:28.338873668 -0700
+++ guile-1.8.8/libguile/Makefile.in	2016-05-27 06:39:08.467267379 -0700
@@ -2512,6 +2512,8 @@
 	@echo '#define SCM_PKGDATA_DIR "$(pkgdatadir)"' >> libpath.tmp
 	@echo '#define SCM_LIBRARY_DIR "$(pkgdatadir)/$(GUILE_EFFECTIVE_VERSION)"'>>libpath.tmp
 	@echo '#define SCM_SITE_DIR "$(pkgdatadir)/site"' >> libpath.tmp
+	@echo '#define SCM_LIB_DIR "$(libdir)"' >> libpath.tmp
+	@echo '#define SCM_EXTENSIONS_DIR "$(pkglibdir)/$(GUILE_EFFECTIVE_VERSION)/extensions"' >> libpath.tmp
 	@echo '#define SCM_BUILD_INFO { \' >> libpath.tmp
 	@echo '	{ "srcdir", "'"`cd @srcdir@; pwd`"'" }, \' >> libpath.tmp
 	@echo ' { "top_srcdir",    "@top_srcdir_absolute@" }, \' >> libpath.tmp
--- guile-1.8.8/libguile/dynl.c.orig	2016-05-26 08:40:55.811650834 -0700
+++ guile-1.8.8/libguile/dynl.c	2016-05-26 08:41:02.492307609 -0700
@@ -47,6 +47,7 @@
 #include <string.h>
 
 #include "libguile/_scm.h"
+#include "libguile/libpath.h"
 #include "libguile/dynl.h"
 #include "libguile/smob.h"
 #include "libguile/keywords.h"
@@ -70,12 +71,76 @@
 */
 /* njrev: not threadsafe, protection needed as described above */
 
+/* LT_PATH_SEP-separated extension library search path, searched last */
+static char *system_extensions_path;
+
 static void *
 sysdep_dynl_link (const char *fname, const char *subr)
 {
   lt_dlhandle handle;
-  handle = lt_dlopenext (fname);
-  if (NULL == handle)
+  if (fname == NULL)
+    /* Return a handle for the program as a whole.  */
+    handle = lt_dlopen (NULL);
+  else
+    {
+      handle = lt_dlopenext (fname);
+
+      if (handle == NULL
+#ifdef LT_DIRSEP_CHAR
+          && strchr (fname, LT_DIRSEP_CHAR) == NULL
+#endif
+          && strchr (fname, '/') == NULL)
+        {
+          /* FNAME contains no directory separators and was not in the
+             usual library search paths, so now we search for it in
+             SYSTEM_EXTENSIONS_PATH. */
+          char *fname_attempt
+            = scm_gc_malloc (strlen (system_extensions_path)
+                             + strlen (fname) + 2,
+                             "dynl fname_attempt");
+          char *path;  /* remaining path to search */
+          char *end;   /* end of current path component */
+          char *s;
+
+          /* Iterate over the components of SYSTEM_EXTENSIONS_PATH */
+          for (path = system_extensions_path;
+               *path != '\0';
+               path = (*end == '\0') ? end : (end + 1))
+            {
+              /* Find end of path component */
+              end = strchr (path, LT_PATHSEP_CHAR);
+              if (end == NULL)
+                end = strchr (path, '\0');
+
+              /* Skip empty path components */
+              if (path == end)
+                continue;
+
+              /* Construct FNAME_ATTEMPT, starting with path component */
+              s = fname_attempt;
+              memcpy (s, path, end - path);
+              s += end - path;
+
+              /* Append directory separator, but avoid duplicates */
+              if (s[-1] != '/'
+#ifdef LT_DIRSEP_CHAR
+                  && s[-1] != LT_DIRSEP_CHAR
+#endif
+                  )
+                *s++ = '/';
+
+              /* Finally, append FNAME (including null terminator) */
+              strcpy (s, fname);
+
+              /* Try to load it, and terminate the search if successful */
+              handle = lt_dlopenext (fname_attempt);
+              if (handle != NULL)
+                break;
+            }
+        }
+    }
+
+  if (handle == NULL)
     {
       SCM fn;
       SCM msg;
@@ -112,7 +177,37 @@
 static void
 sysdep_dynl_init ()
 {
+  char *env;
+
   lt_dlinit ();
+
+  /* Initialize 'system_extensions_path' from
+     $GUILE_SYSTEM_EXTENSIONS_PATH, or if that's not set:
+     <SCM_LIB_DIR> <LT_PATHSEP_CHAR> <SCM_EXTENSIONS_DIR>.
+
+     'lt_dladdsearchdir' can't be used because it is searched before
+     the system-dependent search path, which is the one 'libtool
+     --mode=execute -dlopen' fiddles with (info "(libtool) Libltdl
+     Interface").  See
+     <http://lists.gnu.org/archive/html/guile-devel/2010-11/msg00095.html>.
+
+     The environment variables $LTDL_LIBRARY_PATH and $LD_LIBRARY_PATH
+     can't be used because they would be propagated to subprocesses
+     which may cause problems for other programs.  See
+     <http://lists.gnu.org/archive/html/guile-devel/2012-09/msg00037.html> */
+
+  env = getenv ("GUILE_SYSTEM_EXTENSIONS_PATH");
+  if (env)
+    system_extensions_path = env;
+  else
+    {
+      system_extensions_path
+        = scm_gc_malloc (strlen (SCM_LIB_DIR)
+                         + strlen (SCM_EXTENSIONS_DIR) + 2,
+                         "system_extensions_path");
+      sprintf (system_extensions_path, "%s%c%s",
+               SCM_LIB_DIR, LT_PATHSEP_CHAR, SCM_EXTENSIONS_DIR);
+    }
 }
 
 scm_t_bits scm_tc16_dynamic_obj;