gRPC: fixed possible sign extension of error and setting_value. All cases are harmless and should not happen on valid values, though can result in bad values being shown incorrectly in logs. Found by Coverity (CID 1430311, 1430312, 1430313).

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


# aCC: HP ANSI C++ B3910B A.03.55.02

# C89 mode

CFLAGS="$CFLAGS -Ae"
CC_TEST_FLAGS="-Ae"

PCRE_OPT="$PCRE_OPT -Ae"
ZLIB_OPT="$ZLIB_OPT -Ae"