scons: Add option to enable floating-point textures.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: José Fonseca <jfonseca@vmware.com>

scons/gallium.py

@@ -298,6 +298,10 @@ def generate(env):
         cppdefines += ['BEOS_THREADS']
     if env['embedded']:
         cppdefines += ['PIPE_SUBSYSTEM_EMBEDDED']
+    if env['texture_float']:
+        print 'warning: Floating-point textures enabled.'
+        print 'warning: Please consult docs/patents.txt with your lawyer before building Mesa.'
+        cppdefines += ['TEXTURE_FLOAT_ENABLED']
     env.Append(CPPDEFINES = cppdefines)
 
     # C compiler options