Generate shared libraries rather than a library archive.

This patch should be sent upstream, but needs to be adjusted
to be something that will be properly accepted (probably via
a --enable-shared  option from the configure script).

--- yasm-1.3.0/configure.ac.orig	2015-07-08 11:36:32.537084287 -0700
+++ yasm-1.3.0/configure.ac	2015-07-08 11:38:18.439233048 -0700
@@ -73,9 +73,11 @@
 AC_PROG_CC_STDC
 AC_PROG_INSTALL
 AC_PROG_LN_S
-#automake default ARFLAGS to "cru"
-AC_CHECK_TOOLS(AR,[$AR ar],[ar])
-AC_PROG_RANLIB
+
+# Build shared libraries.
+AC_ENABLE_SHARED
+AC_DISABLE_STATIC
+LT_INIT
 
 # REQUIRE a standard (ANSI/ISO) C compiler
 if test "$ac_cv_prog_cc_stdc" = no; then
--- yasm-1.3.0/Makefile.am.orig	2015-07-08 11:00:30.653026790 -0700
+++ yasm-1.3.0/Makefile.am	2015-07-08 11:00:23.376352265 -0700
@@ -42,9 +42,13 @@
 include tools/Makefile.inc
 
 YASM_MODULES = 
-lib_LIBRARIES = libyasm.a
-libyasm_a_SOURCES =
-nodist_libyasm_a_SOURCES =
+lib_LTLIBRARIES = libyasm.la
+libyasm_la_SOURCES =
+nodist_libyasm_la_SOURCES =
+libyasm_la_CFLAGS=-fPIC
+libyasm_la_CPPFLAGS=-fPIC
+libyasm_la_CXXFLAGS=-fPIC
+libyasm_la_LDFLAGS= -shared -fPIC -version-info 0:0:0
 include modules/Makefile.inc
 
 include libyasm/Makefile.inc