glslang preprocessing: Add -E option to print out preprocessed GLSL, and do the work needed to generate a preprocessed stream. From Andrew Woloszyn <awoloszyn@google.com>.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31508 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/preprocessor.simple.vert

@@ -0,0 +1,22 @@
+#version 310 es
+#define X 1
+#define Y clamp
+#define Z X
+
+#define F 1, 2
+
+#define make_function \
+  float fn ( float x ) \
+  {\
+    return x + 4.0; \
+  }
+
+make_function
+
+int main() {
+  gl_Position = vec4(X);
+  gl_Position = Y(1, 2, 3);
+  gl_Position = vec4(Z);
+  gl_Position = vec4(F);
+  gl_Position = vec4(fn(3));
+}