Add forgotten changes for FindFFmpeg.cmake

Author: h4tr3d

cmake/FindFFmpeg.cmake

@@ -119,7 +119,7 @@ macro(find_component _component _pkgconfig _library _header)
   # in the FIND_PATH() and FIND_LIBRARY() calls
   find_package(PkgConfig)
   if (PKG_CONFIG_FOUND)
-    pkg_check_modules(PC_${_component} REQUIRED ${_pkgconfig})
+    pkg_check_modules(PC_${_component} ${_pkgconfig})
   endif ()
 
   find_path(${_component}_INCLUDE_DIRS ${_header}