autotools: check for dlvsym

As per the previous commit, instead of assuming that Apple doesn't have dlvsym
but everywhere else does, actually check for dlvsym() existing as that function
is glibc-specific.

configure.ac

@@ -137,7 +137,6 @@ AS_CASE([$host_os],
 
   [darwin*], [
     build_wgl=no
-    build_apple=yes
     has_znow=no
     EPOXY_LINK_LIBS=""
   ],
@@ -177,11 +176,6 @@ if test x$build_wgl = xyes; then
     AC_DEFINE([BUILD_WGL], [1], [build WGL tests])
 fi
 
-AM_CONDITIONAL(BUILD_APPLE, test x$build_apple = xyes)
-if test x$build_apple = xyes; then
-    AC_DEFINE([BUILD_APPLE], [1], [build APPLE is apple (for testing)])
-fi
-
 AM_CONDITIONAL(HAS_ZNOW, test x$has_znow = xyes)
 
 AC_CHECK_LIB([GLESv1_CM], [glFlush], [has_gles1=yes], [has_gles1=no])
@@ -190,6 +184,12 @@ AM_CONDITIONAL(HAS_GLES1, test x$has_gles1 = xyes)
 AC_CHECK_LIB([dl], [dlopen], [DLOPEN_LIBS="-ldl"])
 AC_SUBST([DLOPEN_LIBS])
 
+savelibs=$LIBS
+LIBS=$DLOPEN_LIBS
+AC_CHECK_FUNCS([dlvsym], [have_dlvsym=1], [have_dlvsym=0])
+AM_CONDITIONAL(HAVE_DLVSYM, test $have_dlvsym = 1)
+LIBS=$savelibs
+
 VISIBILITY_CFLAGS=""
 AS_CASE(["$host"],
 

test/Makefile.am

@@ -96,7 +96,7 @@ endif
 
 if BUILD_EGL
 if BUILD_GLX
-if !BUILD_APPLE
+if HAVE_DLVSYM
 EGL_AND_GLX_TESTS = \
 	egl_gl \
 	egl_and_glx_different_pointers_egl_glx \
@@ -107,8 +107,8 @@ endif
 endif
 endif
 
-if !BUILD_APPLE
+if HAVE_DLVSYM
-GLX_NON_APPLE_TESTS = \
+GLX_DLVSYM_TESTS = \
 	glx_alias_prefer_same_name \
 	glx_gles2 \
         $()
@@ -122,7 +122,7 @@ GLX_TESTS = \
 	glx_has_extension_nocontext \
 	glx_static \
         $(GLX_SHARED_ZNOW) \
-        $(GLX_NON_APPLE_TESTS) \
+        $(GLX_DLVSYM_TESTS) \
 	$()
 
 GLX_UTIL_LIB = libglx_common.la