toolchain: Replace YASM with NASM

Packages libx264 and ffmpeg are built with ASM options on x86 platforms.
The current libx264 version no longer builds with YASM and requires NASM.
ffmpeg 3.x can be built with either YASM or NASM however, furture 4.x versions
will require NASM.

Signed-off-by: Ted Hess <thess@kitschensync.net>
Acked-by: Rosen Penev <rosenp@gmail.com>

toolchain/nasm/Makefile

@@ -0,0 +1,56 @@
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=nasm
+PKG_VERSION:=2.13.03
+
+PKG_SOURCE_URL:=https://www.nasm.us/pub/nasm/releasebuilds/$(PKG_VERSION)/
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
+
+PKG_HASH:=812ecfb0dcbc5bd409aaa8f61c7de94c5b8752a7b00c632883d15b2ed6452573
+
+HOST_BUILD_PARALLEL:=1
+
+include $(INCLUDE_DIR)/toolchain-build.mk
+
+HOST_CONFIGURE_ARGS+= \
+		--target=$(REAL_GNU_TARGET_NAME) \
+		--with-sysroot=$(TOOLCHAIN_DIR) \
+		--enable-lto \
+		--disable-werror \
+		--disable-gdb \
+		$(SOFT_FLOAT_CONFIG_OPTION) \
+
+define Host/Prepare
+	$(call Host/Prepare/Default)
+	ln -snf $(notdir $(HOST_BUILD_DIR)) $(BUILD_DIR_TOOLCHAIN)/$(PKG_NAME)
+	$(CP) $(SCRIPT_DIR)/config.{guess,sub} $(HOST_BUILD_DIR)/
+endef
+
+define Host/Configure
+	(cd $(HOST_BUILD_DIR); \
+		./autogen.sh \
+	);
+	$(call Host/Configure/Default)
+endef
+
+define Host/Compile
+	+$(MAKE) $(HOST_JOBS) -C $(HOST_BUILD_DIR) all
+endef
+
+define Host/Install
+	$(MAKE) -C $(HOST_BUILD_DIR) \
+		prefix=$(TOOLCHAIN_DIR) \
+		install
+endef
+
+define Host/Clean
+	rm -rf \
+		$(HOST_BUILD_DIR) \
+		$(BUILD_DIR_TOOLCHAIN)/$(PKG_NAME)
+endef
+
+$(eval $(call HostBuild))