bug in the Makefile

[Bill Yuan]

I am still using the FreeBSD10. release version, and it said that the
cdefs.h is not found, but the file was there, I did not touch it. Can
someone help to check

#make
cc -O2 -pipe -DIPFIREWALL -DIPFIREWALL_VERBOSE
-DIPFIREWALL_VERBOSE_LIMIT=1000 -DIPFIREWALL_DEFAULT_TO_ACCEPT
-fno-strict-aliasing -Werror -D_KERNEL -DKLD_MODULE -nostdinc   -I.
-I@ -I@/contrib/altq
-fno-common  -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer  -mno-aes
-mno-avx -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float
 -fno-asynchronous-unwind-tables -ffreestanding -fstack-protector
-std=iso9899:1999 -Qunused-arguments -fstack-protector -Wall
-Wredundant-decls -Wnested-externs -Wstrict-prototypes
 -Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual  -Wundef
-Wno-pointer-sign -fformat-extensions  -Wmissing-include-dirs
-fdiagnostics-show-option  -Wno-error-tautological-compare
-Wno-error-empty-body  -Wno-error-parentheses-equality  -c
/usr/src/sys/modules/ipfw/../../netpfil/ipfw/ip_fw2.c
/usr/src/sys/modules/ipfw/../../netpfil/ipfw/ip_fw2.c:27:10: fatal error:
'sys/cdefs.h' file not found
#include <sys/cdefs.h>
         ^
1 error generated.
*** Error code 1

Stop.
make: stopped in /usr/src/sys/modules/ipfw
#ls /usr/src/sys/sys/cdefs.h
/usr/src/sys/sys/cdefs.h
#