Assorted casts to silence g++ warnings.
diff --git a/src/mesa/glapi/glapi.c b/src/mesa/glapi/glapi.c
index 85330dd..cfa2f8f 100644
--- a/src/mesa/glapi/glapi.c
+++ b/src/mesa/glapi/glapi.c
@@ -673,10 +673,10 @@
             if (ExtEntryTable[i].Offset == offset) {
                return GL_TRUE;  /* offsets match */
             }
-            else if (ExtEntryTable[i].Offset == ~0
+            else if (ExtEntryTable[i].Offset == (GLuint) ~0
                      && offset < DISPATCH_TABLE_SIZE) {
                /* need to patch-up the dispatch code */
-               if (offset != ~0) {
+               if (offset != (GLuint) ~0) {
                   fill_in_entrypoint_offset(ExtEntryTable[i].Address, offset);
                   ExtEntryTable[i].Offset = offset;
                }