Fix build error with gcc-8.5.0.

Author: jfb8856606

lib/Makefile

@@ -130,11 +130,18 @@ endif
 GCCVERGE12 = $(shell expr `gcc -dumpversion | cut -f1 -d.` \>= 12)
 ifeq "$(GCCVERGE12)" "1"
     CFLAGS+= -Wno-error=array-bounds
-    CFLAGS+= -Wno-error=cast-qual
-    CFLAGS+= -Wno-error=format
-    CFLAGS+= -Wno-error=format-extra-args
 endif
 
+# FreeBSD's kernel printf uses %D (hex dump format) which is unknown to GCC's
+# format checker. Disable -Werror=format and -Werror=format-extra-args on every
+# GCC version so the FreeBSD-derived sources still build.
+CFLAGS+= -Wno-error=format
+CFLAGS+= -Wno-error=format-extra-args
+
+# cast-qual is triggered by FreeBSD's atomic_store_ptr macro on every supported
+# GCC version (including GCC 8), so disable -Werror=cast-qual unconditionally.
+CFLAGS+= -Wno-error=cast-qual
+
 GCCVERGE13 = $(shell expr `gcc -dumpversion | cut -f1 -d.` \>= 13)
 ifeq "$(GCCVERGE13)" "1"
     CFLAGS+= -Wno-error=dangling-pointer

mk/kern.mk

@@ -35,7 +35,13 @@ CWARNEXTRA?=	-Wno-error-tautological-compare -Wno-error-empty-body \
 endif
 
 ifeq (${COMPILER_TYPE},gcc)
+# -Wno-address-of-packed-member was added in GCC 9.0, omit it on older GCC
+GCCVER_GE9 := $(shell expr `gcc -dumpversion | cut -f1 -d.` \>= 9)
+ifeq "$(GCCVER_GE9)" "1"
 CWARNEXTRA?=	-Wno-unused-but-set-variable -Wno-address-of-packed-member
+else
+CWARNEXTRA?=	-Wno-unused-but-set-variable
+endif
 endif
 
 #