Introduce TERMUX_PKG_SKIP_SRC_EXTRACT

This new construct allows us to specify the src url in a structured
way for e.g. repology metadata. Start by using it in ack-grep and
ca-certificates.

build-package.sh

@@ -474,7 +474,7 @@ termux_step_start_build() {
 
 # Run just after sourcing $TERMUX_PKG_BUILDER_SCRIPT. May be overridden by packages.
 termux_step_extract_package() {
-	if [ -z "${TERMUX_PKG_SRCURL:=""}" ]; then
+	if [ -z "${TERMUX_PKG_SRCURL:=""}" ] || [ -n "${TERMUX_PKG_SKIP_SRC_EXTRACT:=""}" ]; then
 		mkdir -p "$TERMUX_PKG_SRCDIR"
 		return
 	fi

packages/ack-grep/build.sh

@@ -1,15 +1,18 @@
 TERMUX_PKG_HOMEPAGE=https://beyondgrep.com/
 TERMUX_PKG_DESCRIPTION="Tool like grep optimized for programmers"
 TERMUX_PKG_VERSION=2.22
+TERMUX_PKG_SRCURL=https://beyondgrep.com/ack-${TERMUX_PKG_VERSION}-single-file
+TERMUX_PKG_SHA256=fd0617585b88517a3d41d3d206c1dc38058c57b90dfd88c278049a41aeb5be38
+TERMUX_PKG_SKIP_SRC_EXTRACT=yes
 # Depend on coreutils for bin/env
 TERMUX_PKG_DEPENDS="perl, coreutils"
 TERMUX_PKG_PLATFORM_INDEPENDENT=yes
 
 termux_step_make_install () {
 	termux_download \
-		https://beyondgrep.com/ack-${TERMUX_PKG_VERSION}-single-file \
+		$TERMUX_PKG_SRCURL \
 		$TERMUX_PREFIX/bin/ack \
-		fd0617585b88517a3d41d3d206c1dc38058c57b90dfd88c278049a41aeb5be38
+		$TERMUX_PKG_SHA256
 	touch $TERMUX_PREFIX/bin/ack
 	chmod +x $TERMUX_PREFIX/bin/ack
 }

packages/ca-certificates/build.sh

@@ -1,19 +1,21 @@
 TERMUX_PKG_HOMEPAGE=https://curl.haxx.se/docs/caextract.html
 TERMUX_PKG_DESCRIPTION="Common CA certificates"
 TERMUX_PKG_VERSION=20180620
+TERMUX_PKG_SRCURL=https://curl.haxx.se/ca/cacert.pem
+# If the checksum has changed, it may be time to update the package version:
+TERMUX_PKG_SHA256=238823cd92d3bcdd67c1c278536d6c282dd6b526ee6ee97efbf00ef31d8c5d79
+TERMUX_PKG_SKIP_SRC_EXTRACT=yes
 TERMUX_PKG_PLATFORM_INDEPENDENT=yes
 
 termux_step_make_install () {
 	local CERTDIR=$TERMUX_PREFIX/etc/tls
 	local CERTFILE=$CERTDIR/cert.pem
-	# If the checksum has changed, it may be time to update the package version.
-	local CERTFILE_SHA256=238823cd92d3bcdd67c1c278536d6c282dd6b526ee6ee97efbf00ef31d8c5d79
 
 	mkdir -p $CERTDIR
 
-	termux_download https://curl.haxx.se/ca/cacert.pem \
+	termux_download $TERMUX_PKG_SRCURL \
 		$CERTFILE \
-		$CERTFILE_SHA256
+		$TERMUX_PKG_SHA256
 	touch $CERTFILE
 
 	# Build java keystore which is split out into a ca-certificates-java subpackage: