Allow add extra libraries for OpenSSL

Some platforms such as MSYS2 provide a broken libcrypto.pc, this is needed to fix statically link build.

Configure.cmake

@@ -11,6 +11,7 @@ if (SLEEF_BUILD_STATIC_TEST_BINS)
   set(CMAKE_EXE_LINKER_FLAGS "-static")
 endif()
 
+set(OPENSSL_EXTRA_LIBRARIES "" CACHE STRING "Extra libraries for openssl")
 if (NOT CMAKE_CROSSCOMPILING AND NOT SLEEF_FORCE_FIND_PACKAGE_SSL)
   find_package(OpenSSL)
   if (OPENSSL_FOUND)
@@ -24,6 +25,7 @@ if (NOT CMAKE_CROSSCOMPILING AND NOT SLEEF_FORCE_FIND_PACKAGE_SSL)
              SLEEF_OPENSSL_LIBRARIES "${OPENSSL_LIBRARIES}")
     endif()
     set(SLEEF_OPENSSL_VERSION ${OPENSSL_VERSION})
+    set(SLEEF_OPENSSL_LIBRARIES ${SLEEF_OPENSSL_LIBRARIES} ${OPENSSL_EXTRA_LIBRARIES})
     set(SLEEF_OPENSSL_INCLUDE_DIR ${OPENSSL_INCLUDE_DIR})
   endif()
 else()
@@ -32,7 +34,7 @@ else()
   find_library(LIBCRYPTO crypto)
   if (LIBSSL AND LIBCRYPTO)
     set(SLEEF_OPENSSL_FOUND TRUE)
-    set(SLEEF_OPENSSL_LIBRARIES ${LIBSSL} ${LIBCRYPTO})
+    set(SLEEF_OPENSSL_LIBRARIES ${LIBSSL} ${LIBCRYPTO} ${OPENSSL_EXTRA_LIBRARIES})
     set(SLEEF_OPENSSL_VERSION ${LIBSSL})
   endif()
 endif()