mesa: Autogenerate format_unpack.c

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>

v2 by Samuel Iglesias <siglesias@igalia.com>:
- Add usage of INDENT_FLAGS in Makefile.am

v3 by Samuel Iglesias <siglesias@igalia.com>:
- Modify unpack_float_*() and unpack_ubyte_*() function generation
to use c.datatype() and f.datatype()
- Fix out-of-tree build

v4 by Samuel Iglesias <siglesias@igalia.com>:
- format_unpack.c.mako is now format_unpack.py, with the template code
  inlined. It now auto-generates format_unpack.c
- Add format_unpack.c to gitignore.
- Simplify Makefile.am change
- Modify SConscript to build format_unpack.c with scons

v5 by Samuel Iglesias <siglesias@igalia.com>:
- Don't allow float to non-normalized integer format conversions.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>

src/mesa/SConscript

@@ -73,6 +73,13 @@ format_pack = env.CodeGenerate(
       command = python_cmd + ' $SCRIPT ' + ' $SOURCE > $TARGET'
 )
 
+format_unpack = env.CodeGenerate(
+      target = 'main/format_unpack.c',
+      script = 'main/format_unpack.py',
+      source = 'main/formats.csv',
+      command = python_cmd + ' $SCRIPT ' + ' $SOURCE > $TARGET'
+)
+
 #
 # Assembly sources
 #