[mutter] egl: Expose eglGetProcAddress

[Jonas Ådahl <jadahl src gnome org>]

commit e62cfd90437e9d6dd5a1ca4c52264fce94285df4
Author: Jonas Ådahl <jadahl gmail com>
Date:   Mon Jul 24 17:15:21 2017 +0800

    egl: Expose eglGetProcAddress
    
    It will be needed for OpenGL ES extension function symbol loading.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=785381

 src/backends/meta-egl.c |   19 +++++++++++++++++++
 src/backends/meta-egl.h |    4 ++++
 2 files changed, 23 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-egl.c b/src/backends/meta-egl.c
index 3e3a567..fac21f3 100644
--- a/src/backends/meta-egl.c
+++ b/src/backends/meta-egl.c
@@ -246,6 +246,25 @@ meta_egl_initialize (MetaEgl   *egl,
   return TRUE;
 }
 
+gpointer
+meta_egl_get_proc_address (MetaEgl    *egl,
+                           const char *procname,
+                           GError    **error)
+{
+  gpointer func;
+
+  func = (gpointer) eglGetProcAddress (procname);
+  if (!func)
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Could not load symbol '%s': Not found",
+                   procname);
+      return NULL;
+    }
+
+  return func;
+}
+
 gboolean
 meta_egl_choose_config (MetaEgl      *egl,
                         EGLDisplay    display,
diff --git a/src/backends/meta-egl.h b/src/backends/meta-egl.h
index fea5e00..1bde6fa 100644
--- a/src/backends/meta-egl.h
+++ b/src/backends/meta-egl.h
@@ -52,6 +52,10 @@ gboolean meta_egl_initialize (MetaEgl   *egl,
                               EGLDisplay display,
                               GError   **error);
 
+gpointer meta_egl_get_proc_address (MetaEgl    *egl,
+                                    const char *procname,
+                                    GError    **error);
+
 gboolean meta_egl_choose_config (MetaEgl      *egl,
                                  EGLDisplay    display,
                                  const EGLint *attrib_list,