glsl/builtins: Set the API in the fake context.

Otherwise it gets used uninitialized.

src/glsl/builtin_function.cpp

@@ -36,6 +36,7 @@ gl_shader *
 read_builtins(GLenum target, const char *protos, const char **functions, unsigned count)
 {
    GLcontext fakeCtx;
+   fakeCtx.API = API_OPENGL;
    gl_shader *sh = _mesa_new_shader(NULL, 0, target);
    struct _mesa_glsl_parse_state *st =
       new(sh) _mesa_glsl_parse_state(&fakeCtx, target, sh);

src/glsl/builtins/tools/generate_builtins.py

@@ -129,6 +129,7 @@ gl_shader *
 read_builtins(GLenum target, const char *protos, const char **functions, unsigned count)
 {
    GLcontext fakeCtx;
+   fakeCtx.API = API_OPENGL;
    gl_shader *sh = _mesa_new_shader(NULL, 0, target);
    struct _mesa_glsl_parse_state *st =
       new(sh) _mesa_glsl_parse_state(&fakeCtx, target, sh);