Merge pull request libgit2#6153 from arroz/fix/apple-static-lib

Disabling setting `CMAKE_FIND_LIBRARY_SUFFIXES` on Apple platforms.

Author: ethomson

README.md

@@ -301,6 +301,8 @@ compiler and linker. These flags are rarely used but can be useful for
 - `CMAKE_FIND_ROOT_PATH`: Override the search path for libraries
 - `ZLIB_LIBRARY`, `OPENSSL_SSL_LIBRARY` AND `OPENSSL_CRYPTO_LIBRARY`:
 Tell CMake where to find those specific libraries
+- `LINK_WITH_STATIC_LIBRARIES`: Link only with static versions of
+system libraries
 
 MacOS X
 -------

cmake/DefaultCFlags.cmake

@@ -92,7 +92,7 @@ else()
 		set(CMAKE_C_ARCHIVE_FINISH "<CMAKE_RANLIB> -D <TARGET>")
 	endif()
 
-	if(NOT BUILD_SHARED_LIBS)
+	if(NOT BUILD_SHARED_LIBS AND LINK_WITH_STATIC_LIBRARIES)
 		set(CMAKE_FIND_LIBRARY_SUFFIXES ".a")
 	endif()