glsl-es-1.00: declare some functions that are not builtins in 1.00

Background of this test is that some Android games define these
functions as they are not supposed to exist in GLSL ES 1.00.

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <mesa/piglit!382>

tests/spec/glsl-es-1.00/compiler/non-existent-builtins.vert

+#version 100
+
+/* [config]
+ * expect_result: pass
+ * glsl_version: 1.00
+ * [end config]
+ *
+ * The spec does not list these functions as builtins or reserved words,
+ * we should be able to declare such functions.
+ */
+
+float trunc(float f) { return f; }
+float round(float f) { return f; }
+float roundEven(float f) { return f; }
+float modf(float f) { return f; }
+
+void main()
+{
+    gl_Position = vec4(0.0);
+}
+