meson: Add switch for texture float

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
diff --git a/meson.build b/meson.build
index 02264ae..54230a9 100644
--- a/meson.build
+++ b/meson.build
@@ -37,6 +37,10 @@
 with_tests = get_option('build-tests')
 with_valgrind = get_option('valgrind')
 with_asm = get_option('asm')
+if get_option('texture-float')
+  pre_args += '-DTEXTURE_FLOAT_ENABLED'
+  message('WARNING: Floating-point texture enabled. Please consult docs/patents.txt and your lawyer before building mesa.')
+endif
 
 # XXX: yeah, do these
 with_appledri = false