Add the NO_INCS knob to bsd.prog.mk and bsd.lib.mk to not include

bsd.incs.mk, and use it when installing 32-bit compat libraries
on amd64.  This causes it to *not* overwrite native headers with
i386 versions, which was the case with <fenv.h> and <vgl.h>.

PR:		amd64/83806
Prodded by:	bde
MFC after:	1 week

Makefile.inc1

@@ -237,7 +237,7 @@ LIB32MAKEENV=	MAKEOBJDIRPREFIX=${OBJTREE}/lib32 \
 
 LIB32MAKE=	${LIB32MAKEENV} ${MAKE} -DNO_CPU_CFLAGS -DCOMPAT_32BIT \
 		-DNO_BIND -DNO_MAN -DNO_NLS -DNO_INFO -DNO_HTML
-LIB32IMAKE=	${LIB32MAKE:NINSTALL=*}
+LIB32IMAKE=	${LIB32MAKE:NINSTALL=*} -DNO_INCS
 .endif
 
 # install stage

share/mk/bsd.lib.mk

@@ -244,7 +244,9 @@ _libinstall:
 
 .include <bsd.nls.mk>
 .include <bsd.files.mk>
+.if !defined(NO_INCS)
 .include <bsd.incs.mk>
+.endif
 .include <bsd.links.mk>
 
 .if !defined(NO_MAN)

share/mk/bsd.prog.mk

@@ -174,7 +174,9 @@ NLSNAME?=	${PROG}
 .include <bsd.nls.mk>
 
 .include <bsd.files.mk>
+.if !defined(NO_INCS)
 .include <bsd.incs.mk>
+.endif
 .include <bsd.links.mk>
 
 .if !defined(NO_MAN)