CMake: Fix EXTRA_CFLAGS after commit 29d7856. [skip appveyor]

check_and_add_compiler_option() takes a string, not a variable. Get it
right this time and run CMake builds with a warnings guard again.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 388edd203ffa3d73433e1a676eaff088461391cc..fdd91800f428a46bfcc5ec3bcc4ff1e74de48ff3 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2060,7 +2060,7 @@ endif(NOT MSVC)
 #
 if(NOT "${EXTRA_CFLAGS}" STREQUAL "")
     foreach(_extra_cflag ${EXTRA_CFLAGS})
-        check_and_add_compiler_option(_extra_cflag)
+        check_and_add_compiler_option("${_extra_cflag}")
     endforeach(_extra_cflag)
     message(STATUS "Added extra compile options (${EXTRA_CFLAGS})")
 endif()