glthread: compile marshal_generated.c faster by breaking it up into 8 files

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4270>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4270>
diff --git a/src/mesa/SConscript b/src/mesa/SConscript
index da00374..dafe6c4 100644
--- a/src/mesa/SConscript
+++ b/src/mesa/SConscript
@@ -104,12 +104,13 @@
         pass
 
 # The marshal_generated.c file is generated from the GL/ES API.xml file
-env.CodeGenerate(
-    target = 'main/marshal_generated.c',
-    script = GLAPI + 'gen/gl_marshal.py',
-    source = [GLAPI + 'gen/gl_and_es_API.xml'] + env.Glob(GLAPI + 'gen/*.xml'),
-    command = python_cmd + ' $SCRIPT -f $SOURCE > $TARGET'
-    )
+for i in range(8):
+    env.CodeGenerate(
+        target = 'main/marshal_generated{0}.c'.format(i),
+        script = GLAPI + 'gen/gl_marshal.py',
+        source = [GLAPI + 'gen/gl_and_es_API.xml'] + env.Glob(GLAPI + 'gen/*.xml'),
+        command = python_cmd + ' $SCRIPT -f $SOURCE -i {0} -n 8 > $TARGET'.format(i)
+        )
 
 # The marshal_generated.h file is generated from the GL/ES API.xml file
 env.CodeGenerate(