ES31: Add glGetProgramInterfaceiv API

Add API entry and validation checks(GLES 3.1 section 7.3).
Add the first 4 interfaces(PROGRAM_INPUT, PROGRAM_OUTPUT,
UNIFORM and UNIFORM_BLOCK) implementation.

BUG=angleproject:1920
TEST=angle_end2end_tests:ProgramInterfaceTestES31.*

Change-Id: Iab80ba332e2a5e2b3e677039359e60a420e3d6b0
Reviewed-on: https://chromium-review.googlesource.com/642729
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/queryutils.h b/src/libANGLE/queryutils.h
index e47776c..1ae7343 100644
--- a/src/libANGLE/queryutils.h
+++ b/src/libANGLE/queryutils.h
@@ -136,6 +136,11 @@
                             GLsizei *length,
                             GLint *params);
 
+void QueryProgramInterfaceiv(const Program *program,
+                             GLenum programInterface,
+                             GLenum pname,
+                             GLint *params);
+
 }  // namespace gl
 
 namespace egl