Reduce math function duplication.

Change-Id: If0fe05eff397c8d88753fb2b1a1852722c73602e
Reviewed-on: https://swiftshader-review.googlesource.com/4979
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>

src/OpenGL/libGLES_CM/mathutil.h

diff --git a/src/OpenGL/libGLES_CM/mathutil.h b/src/OpenGL/libGLES_CM/mathutil.h
index b88bcca..89c2e54 100644
--- a/src/OpenGL/libGLES_CM/mathutil.h
+++ b/src/OpenGL/libGLES_CM/mathutil.h
@@ -44,16 +44,8 @@
     return x;
 }
 
-template<typename T, typename MIN, typename MAX>
-inline T clamp(T x, MIN min, MAX max)
-{
-    return x < min ? min : (x > max ? max : x);
-}
-
-inline float clamp01(float x)
-{
-    return clamp(x, 0.0f, 1.0f);
-}
+using sw::clamp;
+using sw::clamp01;
 
 template<const int n>
 inline unsigned int unorm(float x)