makeflags: fix missing -D_FILE_OFFSET_BITS=64 in comment

Interesting things happen when blindly swapping the release-build CCFLAGS
with the debug-build commented-out CCFLAGS.  None of these things that
happen are good.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

makeflags

@@ -1,4 +1,4 @@
 CCFLAGS  = -Wall -Wextra -Werror -O3 -march=native -I../include -ggdb -fpic -D_FILE_OFFSET_BITS=64
-# CCFLAGS  = -Wall -Wextra -Werror -O0 -I../include -ggdb -fpic
+# CCFLAGS  = -Wall -Wextra -Werror -O0 -I../include -ggdb -fpic -D_FILE_OFFSET_BITS=64
 CFLAGS   = $(CCFLAGS) -std=c99
 CXXFLAGS = $(CCFLAGS) -std=c++11 -Wold-style-cast