dbghelp: When the CU is compiled with GCC, deal with some GCC extensions.

dlls/dbghelp/dwarf.c

@@ -781,7 +781,9 @@ compute_location(dwarf2_traverse_context_t* ctx, struct location* loc,
             }
             break;
         default:
+            if (op < DW_OP_lo_user) /* as DW_OP_hi_user is 0xFF, we don't need to test against it */
                 FIXME("Unhandled attr op: %x\n", op);
+            /* FIXME else unhandled extension */
             return loc_err_internal;
         }
     }

dlls/dbghelp/dwarf.h

@@ -376,6 +376,18 @@ typedef enum dwarf_operation_e
   DW_OP_call2                           = 0x98,
   DW_OP_call4                           = 0x99,
   DW_OP_call_ref                        = 0x9a,
+  DW_OP_form_tls_address                = 0x9b,
+  DW_OP_call_frame_cfa                  = 0x9c,
+  DW_OP_bit_piece                       = 0x9d,
+
+  /* Implementation defined extensions */
+  DW_OP_lo_user                         = 0xe0,
+  DW_OP_hi_user                         = 0xff,
+
+  /* GNU extensions */
+  DW_OP_GNU_push_tls_address            = 0xe0,
+  DW_OP_GNU_uninit                      = 0xf0,
+  DW_OP_GNU_encoded_addr                = 0xf1,
 } dwarf_operation_t;
 
 enum dwarf_calling_convention