linker: Make linker_{error,warning} generally available

linker_warning is a new function.  It's identical to linker_error
except that it doesn't set LinkStatus=false and it prepends "warning: "
on messages instead of "error: ".

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 35d893f..19eb9b5 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -178,6 +178,19 @@
 
 
 void
+linker_warning(gl_shader_program *prog, const char *fmt, ...)
+{
+   va_list ap;
+
+   ralloc_strcat(&prog->InfoLog, "error: ");
+   va_start(ap, fmt);
+   ralloc_vasprintf_append(&prog->InfoLog, fmt, ap);
+   va_end(ap);
+
+}
+
+
+void
 invalidate_variable_locations(gl_shader *sh, enum ir_variable_mode mode,
 			      int generic_base)
 {