Include ARCH_FLAGS in CFLAGS when building modules.

[brooks]

Summary

Without this change, modules will match the default compiler configuration
which may not be the same as the kernel values.

[emaste]

It looks like ARCH_FLAGS is used only on MIPS? I'm missing something here since it seems the default MIPS ARCH_FLAGS is set in sys/conf/Makefile.mips, which has CFLAGS+=${EXTRA_FLAGS} $(ARCH_FLAGS)

[imp]

Should have been done when the kernel side of this was committed.

<insert rant about our crazy build system here>

[brooks]

In D11633#241287, @emaste wrote:

It looks like ARCH_FLAGS is used only on MIPS? I'm missing something here since it seems the default MIPS ARCH_FLAGS is set in sys/conf/Makefile.mips, which has CFLAGS+=${EXTRA_FLAGS} $(ARCH_FLAGS)

It does seem to only be used on MIPS. The CFLAGS in Makefile.mips doesn't have any effect on module builds via buildkernel because that's in a clean sub-make invocation whose environment is governed by MKMODULESENV.

I ran into this on CheriBSD where I'm overriding the default -target via ARCH_FLAGS. The initial attempt was via CONF_FLAGS, but that doesn't make it into the trampoline or hack.c's compilation.