Fixed a problem in some CMake versions.

CMakeLists.txt

@@ -67,9 +67,9 @@ IF(CMAKE_COMPILER_IS_GNUCC)
     " PHYSFS_IS_GCC4)
 
     IF(PHYSFS_IS_GCC4)
-        IF((NOT OS2) AND (NOT SOLARIS)) # Not supported on OS/2 or Solaris.
+        IF(NOT OS2 AND NOT SOLARIS) # Not supported on OS/2 or Solaris.
             ADD_DEFINITIONS(-fvisibility=hidden)
-        ENDIF((NOT OS2) AND (NOT SOLARIS))
+        ENDIF(NOT OS2 AND NOT SOLARIS)
     ENDIF(PHYSFS_IS_GCC4)
 ENDIF(CMAKE_COMPILER_IS_GNUCC)