egl: Do not export private symbols

libEGL was incorrectly exporting *all* symbols, public and private.
This patch adds -fvisibility=hidden to libEGL's linker flags to ensure
that only symbols annotated with __attribute__((visibility("default")))
get exported.

Sanity-checked with libEGL's builtin DRI2 driver and the i965 DRI driver
by running Piglit on X/EGL and by running weston-gears on Weston as an
X client.

Sanity-checked with libEGL's Gallium driver (which is not built-in) and
the swrast Gallium driver by running es2gears_x11.

Kristian reviewed the symbol diff in `nm libEGL.so`.

CC: "9.2" <mesa-stable@lists.freedesktop.org>
CC: Ian Romanick <idr@freedesktop.org>
Acked-by: Kristian Høgsberg <krh@bitplanet.net>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>

src/egl/drivers/dri2/Makefile.am

@@ -28,6 +28,7 @@ AM_CFLAGS = \
 	-I$(top_srcdir)/src/egl/wayland/wayland-drm \
 	-I$(top_builddir)/src/egl/wayland/wayland-drm \
 	$(DEFINES) \
+	$(VISIBILITY_CFLAGS) \
 	$(LIBDRM_CFLAGS) \
 	$(LIBUDEV_CFLAGS) \
 	$(LIBKMS_CFLAGS) \

src/egl/drivers/glx/Makefile.am

@@ -22,6 +22,7 @@
 AM_CFLAGS = \
 	-I$(top_srcdir)/include \
 	-I$(top_srcdir)/src/egl/main \
+	$(VISIBILITY_CFLAGS) \
 	$(X11_CFLAGS) \
 	$(DEFINES)
 

src/egl/main/Makefile.am

@@ -27,6 +27,7 @@ AM_CFLAGS = \
 	-I$(top_srcdir)/include \
 	-I$(top_srcdir)/src/gbm/main \
 	$(DEFINES) \
+	$(VISIBILITY_CFLAGS) \
 	$(EGL_CFLAGS) \
 	-D_EGL_NATIVE_PLATFORM=$(EGL_NATIVE_PLATFORM) \
 	-D_EGL_DRIVER_SEARCH_DIR=\"$(EGL_DRIVER_INSTALL_DIR)\" \

src/egl/wayland/wayland-drm/Makefile.am

@@ -1,6 +1,7 @@
 AM_CFLAGS = -I$(top_srcdir)/src/egl/main \
 	    -I$(top_srcdir)/include \
 	    $(DEFINES) \
+	    $(VISIBILITY_CFLAGS) \
 	    $(WAYLAND_CFLAGS) 
 
 noinst_LTLIBRARIES = libwayland-drm.la

src/egl/wayland/wayland-egl/Makefile.am

@@ -2,6 +2,7 @@ pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = wayland-egl.pc
 
 AM_CFLAGS = $(DEFINES) \
+	    $(VISIBILITY_CFLAGS) \
 	    $(WAYLAND_CFLAGS)
 
 lib_LTLIBRARIES = libwayland-egl.la