This patch was developed in-house.  It has been submitted upstream:
http://bugs.python.org/issue23287

--- Python-3.5.3/Lib/ctypes/util.py.~1~	2016-12-17 12:05:05.000000000 +0000
+++ Python-3.5.3/Lib/ctypes/util.py	2016-12-19 08:44:16.426321564 +0000
@@ -214,34 +214,15 @@
 
     elif sys.platform == "sunos5":
 
-        def _findLib_crle(name, is64):
-            if not os.path.exists('/usr/bin/crle'):
-                return None
+        def _findLib_path(name, is64):
 
             env = dict(os.environ)
             env['LC_ALL'] = 'C'
 
             if is64:
-                args = ('/usr/bin/crle', '-64')
+                paths = "/lib/64:/usr/lib/64"
             else:
-                args = ('/usr/bin/crle',)
-
-            paths = None
-            try:
-                proc = subprocess.Popen(args,
-                                        stdout=subprocess.PIPE,
-                                        stderr=subprocess.DEVNULL,
-                                        env=env)
-            except OSError:  # E.g. bad executable
-                return None
-            with proc:
-                for line in proc.stdout:
-                    line = line.strip()
-                    if line.startswith(b'Default Library Path (ELF):'):
-                        paths = os.fsdecode(line).split()[4]
-
-            if not paths:
-                return None
+                paths = "/lib:/usr/lib"
 
             for dir in paths.split(":"):
                 libfile = os.path.join(dir, "lib%s.so" % name)
@@ -251,7 +227,7 @@
             return None
 
         def find_library(name, is64 = False):
-            return _get_soname(_findLib_crle(name, is64) or _findLib_gcc(name))
+            return _get_soname(_findLib_path(name, is64) or _findLib_gcc(name))
 
     else: