termux_step_start_build: define TERMUX_STANDALONE_TOOLCHAIN before so…

…urcing the package's build script, so the host build can use it if wanted

scripts/build/termux_step_start_build.sh

@@ -1,4 +1,9 @@
 termux_step_start_build() {
+	TERMUX_STANDALONE_TOOLCHAIN="$TERMUX_COMMON_CACHEDIR/android-r${TERMUX_NDK_VERSION}-api-${TERMUX_PKG_API_LEVEL}"
+	# Bump the below version if a change is made in toolchain setup to ensure
+	# that everyone gets an updated toolchain:
+	TERMUX_STANDALONE_TOOLCHAIN+="-v3"
+
 	# shellcheck source=/dev/null
 	source "$TERMUX_PKG_BUILDER_SCRIPT"
 
@@ -8,11 +13,6 @@ termux_step_start_build() {
 		TERMUX_PKG_PLATFORM_INDEPENDENT=true
 	fi
 
-	TERMUX_STANDALONE_TOOLCHAIN="$TERMUX_COMMON_CACHEDIR/android-r${TERMUX_NDK_VERSION}-api-${TERMUX_PKG_API_LEVEL}"
-	# Bump the below version if a change is made in toolchain setup to ensure
-	# that everyone gets an updated toolchain:
-	TERMUX_STANDALONE_TOOLCHAIN+="-v3"
-
 	if [ -n "${TERMUX_PKG_BLACKLISTED_ARCHES:=""}" ] && [ "$TERMUX_PKG_BLACKLISTED_ARCHES" != "${TERMUX_PKG_BLACKLISTED_ARCHES/$TERMUX_ARCH/}" ]; then
 		echo "Skipping building $TERMUX_PKG_NAME for arch $TERMUX_ARCH"
 		exit 0