FindRuby: Fix cache strings

Modules/FindRuby.cmake

@@ -431,6 +431,8 @@ if (Ruby_EXECUTABLE AND NOT Ruby_EXECUTABLE STREQUAL "${_Ruby_EXECUTABLE_LAST_QU
   set(Ruby_RUBY_LIB_DIR ${Ruby_RUBY_LIB_DIR} CACHE INTERNAL "The Ruby ruby-lib dir" FORCE)
   set(_Ruby_SO_NAME ${_Ruby_SO_NAME} CACHE PATH "The Ruby shared library name" FORCE)
   set(_Ruby_DLEXT ${_Ruby_DLEXT} CACHE PATH "Ruby extensions extension" FORCE)
+  set(_Ruby_SO_NAME ${_Ruby_SO_NAME} CACHE STRING "The Ruby shared library name" FORCE)
+  set(_Ruby_DLEXT ${_Ruby_DLEXT} CACHE STRING "Ruby extensions extension" FORCE)
   set(Ruby_SITEARCH_DIR ${Ruby_SITEARCH_DIR} CACHE INTERNAL "The Ruby site arch dir" FORCE)
   set(Ruby_SITELIB_DIR ${Ruby_SITELIB_DIR} CACHE INTERNAL "The Ruby site lib dir" FORCE)
   set(Ruby_HAS_VENDOR_RUBY ${Ruby_HAS_VENDOR_RUBY} CACHE BOOL "Vendor Ruby is available" FORCE)