mesa: Add a flag for forcing all GLSL extensions to "warn".

NOTE: This is a candidate for the 8.0 branch.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
(cherry picked from commit b9e27cc142)

src/glsl/glsl_parser_extras.cpp

@@ -114,6 +114,9 @@ _mesa_glsl_parse_state::_mesa_glsl_parse_state(struct gl_context *ctx,
    }
 
    this->supported_version_string = supported;
+
+   if (ctx->Const.ForceGLSLExtensionsWarn)
+      _mesa_glsl_process_extension("all", NULL, "warn", NULL, this);
 }
 
 const char *

src/mesa/main/mtypes.h

@@ -2772,6 +2772,12 @@ struct gl_constants
 
    GLuint GLSLVersion;  /**< GLSL version supported (ex: 120 = 1.20) */
 
+   /**
+    * Changes default GLSL extension behavior from "error" to "warn".  It's out
+    * of spec, but it can make some apps work that otherwise wouldn't.
+    */
+   GLboolean ForceGLSLExtensionsWarn;
+
    /**
     * Does the driver support real 32-bit integers?  (Otherwise, integers are
     * simulated via floats.)