[benchmark] Fix win32 link on case-sensitive fs

Summary: This fixes cross-builds with MinGW from case-sensitive file-systems (on Linux)

This is a cherry-pick from
https://github.com/google/benchmark/pull/840
https://github.com/google/benchmark/commit/8e48105d465c586068dd8e248fe75a8971c6ba3a

Original patch by: @jschueller (Julien Schueller) !

Differential Revision: https://reviews.llvm.org/D61371

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@367356 91177308-0d34-0410-b5e6-96231b3b80d8

utils/google-benchmark/README.LLVM

@@ -10,3 +10,7 @@ Changes:
   is applied on top of
   https://github.com/google/benchmark/commit/4528c76b718acc9b57956f63069c699ae21edcab
   to add RISC-V timer support.
+* https://github.com/google/benchmark/commit/8e48105d465c586068dd8e248fe75a8971c6ba3a
+  is applied on top of
+  https://github.com/google/benchmark/commit/4528c76b718acc9b57956f63069c699ae21edcab
+  to fix cross-build from linux to windows via MinGW.

utils/google-benchmark/src/CMakeLists.txt

@@ -35,7 +35,7 @@ endif()
 
 # We need extra libraries on Windows
 if(${CMAKE_SYSTEM_NAME} MATCHES "Windows")
-  target_link_libraries(benchmark Shlwapi)
+  target_link_libraries(benchmark shlwapi)
 endif()
 
 # We need extra libraries on Solaris