Allow overriding the tool used for stripping binaries

Since the make variable STRIP is already used for other purposes, this
uses STRIPBIN (which is also used for the same purpose by install(1).
This allows using LLVM objcopy to strip binaries instead of the in-tree
elftoolchain objcopy. We make use of this in CheriBSD since passing
binaries generated by our toolchain to elftoolchain strip sometimes results
in assertion failures.

This allows working around https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=248516
by specifying STRIPBIN=/path/to/llvm-strip

Obtained from:	CheriBSD
Reviewed By:	emaste, brooks
Differential Revision: https://reviews.freebsd.org/D25988

Makefile.inc1

@@ -180,7 +180,7 @@ MK_SYSTEM_LINKER=	no
 .if defined(CROSS_TOOLCHAIN_PREFIX)
 CROSS_BINUTILS_PREFIX?=${CROSS_TOOLCHAIN_PREFIX}
 .endif
-XBINUTILS=	AS AR LD NM OBJCOPY RANLIB SIZE STRINGS
+XBINUTILS=	AS AR LD NM OBJCOPY RANLIB SIZE STRINGS STRIPBIN
 .for BINUTIL in ${XBINUTILS}
 .if defined(CROSS_BINUTILS_PREFIX) && \
     exists(${CROSS_BINUTILS_PREFIX}/${${BINUTIL}})
@@ -755,7 +755,7 @@ CROSSENV+=	CC="${XCC} ${XCFLAGS}" CXX="${XCXX} ${XCXXFLAGS} ${XCFLAGS}" \
 		AS="${XAS}" AR="${XAR}" LD="${XLD}" LLVM_LINK="${XLLVM_LINK}" \
 		NM=${XNM} OBJCOPY="${XOBJCOPY}" \
 		RANLIB=${XRANLIB} STRINGS=${XSTRINGS} \
-		SIZE="${XSIZE}"
+		SIZE="${XSIZE}" STRIPBIN="${XSTRIPBIN}"
 
 .if defined(CROSS_BINUTILS_PREFIX) && exists(${CROSS_BINUTILS_PREFIX})
 # In the case of xdev-build tools, CROSS_BINUTILS_PREFIX won't be a

share/mk/sys.mk

@@ -275,6 +275,7 @@ SHELL		?=	sh
 
 .if !defined(%POSIX)
 SIZE		?=	size
+STRIPBIN	?=	strip
 .endif
 
 YACC		?=	yacc

stand/i386/loader/Makefile

@@ -64,7 +64,7 @@ ${LOADER}: ${LOADER}.bin ${BTXLDR} ${BTXKERN}
 		-b ${BTXKERN} ${LOADER}.bin
 
 ${LOADER}.bin: ${LOADER}.sym
-	strip -R .comment -R .note -o ${.TARGET} ${.ALLSRC}
+	${STRIPBIN} -R .comment -R .note -o ${.TARGET} ${.ALLSRC}
 
 .if ${MK_LOADER_ZFS} == "yes" && ${LOADER_INTERP} == ${LOADER_DEFAULT_INTERP}
 LINKS+=		${BINDIR}/${LOADER} ${BINDIR}/zfsloader

sys/modules/linux/Makefile

@@ -69,12 +69,12 @@ linux${SFX}_support.o: linux${SFX}_assym.h assym.inc
 ${VDSO}.so: linux${SFX}_locore.o
 	${OBJCOPY} --input-target binary --output-target elf64-x86-64-freebsd			\
 	    --binary-architecture i386 linux${SFX}_locore.o ${.TARGET}
-	strip -N _binary_linux${SFX}_locore_o_size ${.TARGET}
+	${STRIPBIN} -N _binary_linux${SFX}_locore_o_size ${.TARGET}
 .else
 ${VDSO}.so: linux${SFX}_locore.o
 	${OBJCOPY} --input-target binary --output-target elf32-i386-freebsd			\
 	    --binary-architecture i386 linux${SFX}_locore.o ${.TARGET}
-	strip -N _binary_linux_locore_o_size ${.TARGET}
+	${STRIPBIN} -N _binary_linux_locore_o_size ${.TARGET}
 .endif
 
 linux${SFX}_genassym.o: offset.inc

sys/modules/linux64/Makefile

@@ -46,7 +46,7 @@ OBJCOPY_TARGET=--output-target elf64-x86-64 --binary-architecture i386:x86-64
 ${VDSO}.so: linux_locore.o
 	${OBJCOPY} --input-target binary ${OBJCOPY_TARGET} -S -g \
 	    linux_locore.o ${.TARGET}
-	strip -N _binary_linux_locore_o_size ${.TARGET}
+	${STRIPBIN} -N _binary_linux_locore_o_size ${.TARGET}
 
 linux_support.o: assym.inc linux_assym.h
 	${CC} -c -x assembler-with-cpp -DLOCORE ${CFLAGS} \