demangler/gcc3+: when the parameter isn't found, return a useful error.

after the last argument, get_next_argument() would call get_next_argument_gcc3(),
see a failure, then call get_next_argument_gcc2(). Ideally we could make
different cookies for gcc2 and gcc3+ demanglers, thus avoiding this issue.

Change-Id: I3904e008a0b6ba627940fb9bca1d44ddbafbcbd0
Reviewed-on: https://review.haiku-os.org/742
Reviewed-by: waddlesplash <[email protected]>

src/add-ons/kernel/debugger/demangle/demangle.cpp

@@ -46,8 +46,8 @@ get_next_argument(uint32* _cookie, const char* mangledName, char* name,
 	if (looks_like_gcc3_symbol(mangledName)) {
 		status_t error = get_next_argument_gcc3(_cookie, mangledName, name,
 			nameSize, _type, _argumentLength);
-		if (error == B_OK)
-			return B_OK;
+		if (error == B_OK || error == B_BAD_INDEX)
+			return error;
 	}
 
 	// fallback is gcc2

src/add-ons/kernel/debugger/demangle/gcc3+.cpp

@@ -3726,6 +3726,8 @@ get_next_argument_gcc3(uint32* _cookie, const char* mangledName, char* name,
 				return B_BUFFER_OVERFLOW;
 			case ERROR_NO_MEMORY:
 				return B_NO_MEMORY;
+			case ERROR_INVALID_PARAMETER_INDEX:
+				return B_BAD_INDEX;
 			case ERROR_INTERNAL:
 			default:
 				return B_ERROR;