Building head on stable/11 requires libzstd

Add lib/libzstd to _elftoolchain_libs

tools/build/Makefile needs to create the install dir for libzstd
Since this would make the line too long, rework to use a list
in one per line format (easier to add in future)
and dispense with the .for loop

Reviewed by:	emaste bapt
Differential Revision:	https://reviews.freebsd.org/D220134

Makefile.inc1

@@ -2159,7 +2159,7 @@ _bootstrap_tools_links+=m4 lex
 # r339083 libelf: correct mips64el test to use ELF header
 # r348347 Add missing powerpc64 relocation support to libdwarf
 .if ${BOOTSTRAPPING} < 1300030
-_elftoolchain_libs= lib/libelf lib/libdwarf
+_elftoolchain_libs= lib/libelf lib/libdwarf lib/libzstd
 ${_bt}-lib/libelf: ${_bt_m4_depend}
 ${_bt}-lib/libdwarf: ${_bt_m4_depend}
 .endif
@@ -2361,7 +2361,6 @@ ${_bt}-link-${_tool}: .PHONY .MAKE
 ${_bt}-links: ${_bt}-link-${_tool}
 .endfor
 
-
 bootstrap-tools: ${_bt}-links .PHONY
 
 #	Please document (add comment) why something is in 'bootstrap-tools'.

tools/build/Makefile

@@ -120,10 +120,17 @@ host-symlinks:
 # Create all the directories that are needed during the legacy, bootstrap-tools
 # and cross-tools stages. We do this here using mkdir since mtree may not exist
 # yet (this happens if we are crossbuilding from Linux/Mac).
+INSTALLDIR_LIST= \
+	bin \
+	lib/casper \
+	lib/geom \
+	usr/include/casper \
+	usr/include/private/zstd \
+	usr/lib \
+
 installdirs:
-.for _dir in bin usr/lib usr/include usr/include/casper lib/geom lib/casper
-	mkdir -p "${DESTDIR}/${_dir}"
-.endfor
+	mkdir -p ${INSTALLDIR_LIST:S,^,${DESTDIR}/,}
+
 # Link usr/bin, sbin, and usr/sbin to bin so that it doesn't matter whether a
 # bootstrap tool was added to WORLTMP with a symlink or by building it in the
 # bootstrap-tools phase. We could also overrride BINDIR when building bootstrap