tools: build autoconf, automake, libtool, dosfstools and make-ext4fs in parallel

libtool      22.5 s -> 20.0 s
  dosfstools    6.0 s ->  4.8 s
  make-ext4fs   2.1 s ->  1.2 s
  automake      3.9 s ->  3.4 s
  autoconf      3.1 s ->  2.6 s

Each one builds five times out of five with the job server, and each
build installs files that are identical to those of a serial build.

Signed-off-by: John Crispin <john@phrozen.org>

tools/autoconf/Makefile

@@ -13,6 +13,8 @@ PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=@GNU/autoconf
 PKG_HASH:=ba885c1319578d6c94d46e9b0dceb4014caafe2490e437a0dbca3f270a223f5a
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/host-build.mk
 
 HOST_CONFIGURE_VARS += \

tools/automake/Makefile

@@ -15,6 +15,8 @@ PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@GNU/automake
 PKG_HASH:=63e585246d0fc8772dffdee0724f2f988146d1a3f1c756a3dc5cfbefa3c01915
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/host-build.mk
 
 HOST_CONFIGURE_ARGS += \

tools/dosfstools/Makefile

@@ -17,6 +17,7 @@ PKG_SOURCE_URL:=https://github.com/dosfstools/dosfstools/releases/download/v$(PK
 PKG_HASH:=64926eebf90092dca21b14259a5301b7b98e7b1943e8a201c7d726084809b527
 
 HOST_FIXUP:=autoreconf
+HOST_BUILD_PARALLEL:=1
 
 include $(INCLUDE_DIR)/host-build.mk
 

tools/libtool/Makefile

@@ -14,6 +14,8 @@ PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=@GNU/$(PKG_NAME)
 PKG_HASH:=da8ebb2ce4dcf46b90098daf962cffa68f4b4f62ea60f798d0ef12929ede6adf
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/host-build.mk
 
 export GNULIB_SRCDIR:=$(HOST_GNULIB_SRCDIR)

tools/make-ext4fs/Makefile

@@ -15,6 +15,8 @@ PKG_SOURCE_DATE:=2025-05-02
 PKG_SOURCE_VERSION:=13767a96fcdffd59fef16f1b86919f63b6dee45a
 PKG_MIRROR_HASH:=4fc8c5c2a550a3978648411d4bff83730c580b6e54194826461830299b21b680
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/host-build.mk
 
 define Host/Install