[build] Disable dangling pointer checking for GCC

The dangling pointer warning introduced in GCC 12 reports false
positives that result in build failures.  In particular, storing the
address of a local code label used to record the current state of a
state machine (as done in crypto/deflate.c) is reported as an error.

There seems to be no way to mark the pointer type as being permitted
to hold such a value, so unconditionally disable the warning.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile.housekeeping

diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index 61a9cf0..658b84b 100644
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -461,8 +461,10 @@
 ifeq ($(CCTYPE),gcc)
 CFLAGS		+= -ffreestanding
 CFLAGS		+= -fcommon
-CFLAGS		+= -Wall -W -Wformat-nonliteral -Wno-array-bounds
-HOST_CFLAGS	+= -Wall -W -Wformat-nonliteral -Wno-array-bounds
+CFLAGS		+= -Wall -W -Wformat-nonliteral
+CFLAGS		+= -Wno-array-bounds -Wno-dangling-pointer
+HOST_CFLAGS	+= -Wall -W -Wformat-nonliteral
+HOST_CFLAGS	+= -Wno-array-bounds -Wno-dangling-pointer
 endif
 CFLAGS		+= $(WORKAROUND_CFLAGS) $(EXTRA_CFLAGS)
 ASFLAGS		+= $(WORKAROUND_ASFLAGS) $(EXTRA_ASFLAGS)