mesa: rename format_info.c to format_info.h

The file is auto-generated, and #included by formats.c. Let's rename it
to reflect the latter. This will also help up fix the dependency
tracking by adding it to the _SOURCES variable, without the side effect
of it being compiled (twice).

v2: Update .gitignore to reflect the rename.

Cc: "10.4, 10.5" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
diff --git a/src/mesa/SConscript b/src/mesa/SConscript
index d6ff083..81939f9 100644
--- a/src/mesa/SConscript
+++ b/src/mesa/SConscript
@@ -64,7 +64,7 @@
 )
 
 format_info = env.CodeGenerate(
-      target = 'main/format_info.c',
+      target = 'main/format_info.h',
       script = 'main/format_info.py',
       source = 'main/formats.csv',
       command = python_cmd + ' $SCRIPT ' + ' $SOURCE > $TARGET'