targets/libgl-xlib: hide all the exported symbol mayhem

Leave only the gl/glx and mangled gl symbols.
XMesa* was never an official interface and the only
user of it was mesa-demos, while they were still in
the same repo as mesa.

v2: Conditionally use the version-script.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

src/gallium/targets/libgl-xlib/Makefile.am

@@ -50,6 +50,11 @@ lib@GL_LIB@_la_LDFLAGS = \
 	$(GC_SECTIONS) \
 	$(LD_NO_UNDEFINED)
 
+if HAVE_LD_VERSION_SCRIPT
+lib@GL_LIB@_la_LDFLAGS += \
+	-Wl,--version-script=$(top_srcdir)/src/gallium/targets/libgl-xlib/libgl-xlib.sym
+endif
+
 lib@GL_LIB@_la_LIBADD = \
 	$(top_builddir)/src/gallium/state_trackers/glx/xlib/libxlib.la \
 	$(top_builddir)/src/gallium/winsys/sw/xlib/libws_xlib.la \

src/gallium/targets/libgl-xlib/libgl-xlib.sym

@@ -0,0 +1,7 @@
+{
+	global:
+		gl*;
+		mgl*;
+	local:
+		*;
+};