Summary:
Replace `-o /dev/null` by `-o test.o` when testing for C++ features such as
-faligned-new otherwise tests will fail with some bugged binutils
(https://sourceware.org/bugzilla/show_bug.cgi?id=19526):
```
output/host/bin/xtensa-buildroot-linux-uclibc-g++ -faligned-new -x c++ - -o /dev/null <<EOF
struct alignas(1024) t {int a;};
int main() {}
EOF
/home/fabrice/buildroot/output/host/lib/gcc/xtensa-buildroot-linux-uclibc/8.3.0/../../../../xtensa-buildroot-linux-uclibc/bin/ld: final link failed: file truncated
```
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6479
Reviewed By: ajkr
Differential Revision: D33574136
Pulled By: riversand963
fbshipit-source-id: 12b48658b17e36013042c98219b89ddf71161d3c
53c8f739fd