Description of problem:
We build our package (nss) with -Werror=maybe-uninitialized, but only on s390x, the warning is issued.  Conceptually, the relevant code is something like:
```
    int value;
[...]
    parseNextCmdInput(extKeyUsageKeyWordArray, &value, &nextPos,
                      &isCriticalExt); /* assign value */
[...]
    keyUsage |= (0x80 >> value); /* 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized] */
```
though there are some indirections with functions and macros.

Version-Release number of selected component (if applicable):
10.0.1-0.7.fc32

How reproducible:
100%

Steps to Reproduce:
1. fedpkg clone nss
2. cd nss
3. fedpkg scratch-build --arches s390x

Actual results:
build error

Expected results:
build succeeds

Additional info:
The complete log around the failure:
```
cc -o Linux5.4_s390x_cc_glibc_PTH_64_OPT.OBJ/certext.o -c -std=c99 -O2 -fPIC   -pipe -ffunction-sections -fdata-sections -DHAVE_STRERROR -DLINUX -Dlinux -Wall -Wshadow -Werror -DXP_UNIX -DNSPR20 -UDEBUG -DNDEBUG -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_POSIX_SOURCE -D_REENTRANT -DUSE_UTIL_DIRECTLY -DNO_NSPR_10_SUPPORT -DSSL_DISABLE_DEPRECATED_CIPHER_SUITE_NAMES -I/usr/include/nspr4  -iquote ../../../dist/Linux5.4_s390x_cc_glibc_PTH_64_OPT.OBJ/../public/nss -iquote ../../../dist/Linux5.4_s390x_cc_glibc_PTH_64_OPT.OBJ/../private/nss -I../../../dist/Linux5.4_s390x_cc_glibc_PTH_64_OPT.OBJ/include -I../../../dist/public/nss  -I../../../dist/private/nss  -I../../../dist/public/dbm -I../../../dist/public/seccmd -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=zEC12 -mtune=z13 -fasynchronous-unwind-tables -fstack-clash-protection certext.c
certext.c: In function 'AddExtKeyUsage':
certext.c:513:9: error: 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  513 |     int value;
      |         ^~~~~
certext.c: In function 'AddExtensions':
certext.c:706:31: error: 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  706 |             keyUsage |= (0x80 >> value);
      |                         ~~~~~~^~~~~~~~~
certext.c:667:9: note: 'value' was declared here
  667 |     int value;
      |         ^~~~~
certext.c:368:31: error: 'value' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  368 |             keyUsage |= (0x80 >> value);
      |                         ~~~~~~^~~~~~~~~
certext.c:330:9: note: 'value' was declared here
  330 |     int value;
      |         ^~~~~
cc1: all warnings being treated as errors
```