cmake: FindNGHTTP2 add static lib name to find_library call

Add the static library name, nghttp2_static as a name to search.

This provides cmake parity with the winbuild Makefile.vc allowing
the cmake build to find and allow the link to static nghttp2 library.

CMake/FindNGHTTP2.cmake

@@ -25,7 +25,7 @@ include(FindPackageHandleStandardArgs)
 
 find_path(NGHTTP2_INCLUDE_DIR "nghttp2/nghttp2.h")
 
-find_library(NGHTTP2_LIBRARY NAMES nghttp2)
+find_library(NGHTTP2_LIBRARY NAMES nghttp2 nghttp2_static)
 
 find_package_handle_standard_args(NGHTTP2
     FOUND_VAR