make depend error

[Suken]

list:
while buiding a kernel today,the error occured at make depend.Is it
related gcc imported?
...
cc -c -O -pipe -Wall -Wredundant-decls -Wnested-externs
-Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Winline
-Wcast-qual -fformat-extensions -std=c99 -g -nostdinc -I- -I.
-I/usr/src/sys -I/usr/src/sys/contrib/dev/acpica
-I/usr/src/sys/contrib/altq -I/usr/src/sys/contrib/ipfilter
-I/usr/src/sys/contrib/pf -I/usr/src/sys/contrib/dev/ath
-I/usr/src/sys/contrib/dev/ath/freebsd -I/usr/src/sys/contrib/ngatm
-D_KERNEL -include opt_global.h -finline-limit=8000 --param
inline-unit-growth=100 --param large-function-growth=1000
-mno-align-long-strings
-mpreferred-stack-boundary=2 -ffreestanding
/usr/src/sys/i386/i386/genassym.c
cc1: error: unrecognized command line option "-fformat-extensions"

TIA