Revert "mesa: Don't add 1 to GL_ACTIVE_UNIFORM_MAX_LENGTH."

This reverts commit 001a7bfdfc.  I
hadn't found the section of the spec clarifying that the old behavior
was right.  Reverting fixes the new version of the testcase, and the
Humus demos that could no longer find their uniforms.

Bug #29782
Bug #29783

src/mesa/main/shaderapi.c

@@ -644,6 +644,8 @@ get_programiv(GLcontext *ctx, GLuint program, GLenum pname, GLint *params)
       break;
    case GL_ACTIVE_UNIFORM_MAX_LENGTH:
       *params = _mesa_longest_uniform_name(shProg->Uniforms);
+      if (*params > 0)
+         (*params)++;  /* add one for terminating zero */
       break;
    case GL_PROGRAM_BINARY_LENGTH_OES:
       *params = 0;