glsl/standalone_scaffolding: Add stub for _mesa_warning()

A subsequent patch will add mesa/main/imports.c as a dependency to the
compiler, which in turn requires that _mesa_warning() be defined.

The real definition of _mesa_warning() is in mesa/main/errors.c, but to
pull that file into the standalone scaffolding would require transitively
pulling in the dispatch tables.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Acked-by: Paul Berry <stereotype441@gmail.com>
Signed-off-by: Chad Versace <chad.versace@linux.intel.com>

src/glsl/standalone_scaffolding.cpp

@@ -33,6 +33,24 @@
 #include <string.h>
 #include "ralloc.h"
 
+void
+_mesa_warning(struct gl_context *ctx, const char *fmt, ...)
+{
+    va_list vargs;
+    (void) ctx;
+
+    va_start(vargs, fmt);
+
+    /* This output is not thread-safe, but that's good enough for the
+     * standalone compiler.
+     */
+    fprintf(stderr, "Mesa warning: ");
+    vfprintf(stderr, fmt, vargs);
+    fprintf(stderr, "\n");
+
+    va_end(vargs);
+}
+
 void
 _mesa_reference_shader(struct gl_context *ctx, struct gl_shader **ptr,
                        struct gl_shader *sh)

src/glsl/standalone_scaffolding.h

@@ -33,6 +33,9 @@
 
 #include "main/mtypes.h"
 
+extern "C" void
+_mesa_warning(struct gl_context *ctx, const char *fmtString, ... );
+
 extern "C" void
 _mesa_reference_shader(struct gl_context *ctx, struct gl_shader **ptr,
                        struct gl_shader *sh);