scons: add code to generate the various GL API files
This fixes recent build breakage when we began building the generated
API files from xml as part of the normal build process.
Fixes http://bugs.freedesktop.org/show_bug.cgi?id=50475
diff --git a/src/mesa/SConscript b/src/mesa/SConscript
index d7932c7..99bdfad 100644
--- a/src/mesa/SConscript
+++ b/src/mesa/SConscript
@@ -6,6 +6,7 @@
 import filecmp
 import os
 import subprocess
+from sys import executable as python_cmd
 
 env = env.Clone()
 
@@ -328,8 +329,9 @@
     statetracker_sources
 )
 
+GLAPI = '#src/mapi/glapi/'
+
 if env['gles']:
-    from sys import executable as python_cmd
 
     env.Append(CPPDEFINES = ['FEATURE_ES1=1', 'FEATURE_ES2=1'])
 
@@ -349,7 +351,6 @@
     )
 
     # generate GLES headers
-    GLAPI = '#src/mapi/glapi/'
     gles_headers = []
     gles_headers += env.CodeGenerate(
         target = 'main/api_exec_es1_dispatch.h',
@@ -452,6 +453,16 @@
         env.Append(CPPPATH = [matypes[0].dir])
 
 
+# The enums.c file is generated from the GL/ES API.xml file
+env.CodeGenerate(
+    target = 'main/enums.c',
+    script = GLAPI + 'gen/gl_enums.py',
+    source = GLAPI + 'gen/gl_and_es_API.xml',
+    command = python_cmd + ' $SCRIPT -f $SOURCE > $TARGET'
+    )
+
+# We also depend on the auto-generated GL API headers
+env.Depends(mesa_sources, glapi_headers)
 
 
 def write_git_sha1_h_file(filename):