The Solaris/amd64 buildbot
<https://lab.llvm.org/staging/#/builders/101/builds/2845> has recently been
broken several times, at least one of those remains unfixed:
[63/446] Generating Sanitizer-x86_64-Test
[...]
Undefined first referenced
symbol in file
_ZN11__sanitizer15internal_usleepEy /opt/llvm-buildbot/home/solaris11-amd64/clang-solaris11-amd64/stage1/projects/compiler-rt/lib/sanitizer_common/tests/libRTSanitizerCommon.test.x86_64.a(sanitizer_common.cpp.o)
ld: fatal: symbol referencing errors
Thist patch fixes it by defining the missing `internal_usleep`.
Tested on `amd64-pc-solaris2.11.`
Differential Revision: https://reviews.llvm.org/D105878