luafilesystems: unbreak builds with largefile support

A typo was introduced in e6c4ce6c (luafilesystem: remove LARGE_FILE
constraint), breaking the build when largefile support was enabled.

Reported-by: Marcus Osdoba <marcus.osdoba@googlemail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/luafilesystem/luafilesystem.mk

@@ -9,7 +9,7 @@ LUAFILESYSTEM_SITE = http://github.com/downloads/keplerproject/luafilesystem
 LUAFILESYSTEM_DEPENDENCIES = lua
 
 ifeq ($(BR2_LARGEFILE),y)
-LFS_CFLAGS = -D_FILE_OFFSET_BITS=64 _LARGEFILE64_SOURCE
+LFS_CFLAGS = -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE
 endif
 
 define LUAFILESYSTEM_BUILD_CMDS