osmo-build-dep.sh: cd into subdir before building

Support building the legacy openbsc source with osmo-build.dep.sh. This
will be used by the upcoming osmocom-build-old-tags-against-master.sh
script.

Related: OS#3765
Change-Id: I852e103e80bf295f692cf13c4cb38e80fbc19eca

scripts/common.sh

@@ -59,3 +59,13 @@ osmo_git_last_tags() {
 	ret="$(osmo_git_last_commits_tags "$1" "$2" "$3")"
 	echo "$ret" | cut -d/ -f 3
 }
+
+# Print the subdirectory of the repository where the source lies (configure.ac etc.).
+# Print nothing when the source is in the topdir of the repository.
+osmo_source_subdir() {
+	case "$1" in
+		openbsc)
+			echo "openbsc"
+			;;
+	esac
+}

scripts/osmo-build-dep.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+. "$(dirname "$0")/common.sh"
 
 project="$1"
 branch="$2"
@@ -48,6 +49,11 @@ cd "$project"
 # of the -I and -L search paths
 mkdir -p "$inst/stow"
 
+subdir="$(osmo_source_subdir "$project")"
+if [ -n "$subdir" ]; then
+	cd "$subdir"
+fi
+
 autoreconf --install --force
 ./configure --prefix="$inst/stow/$project" --with-systemdsystemunitdir="$inst/stow/$project/lib/systemd/system" $cfg
 $MAKE $PARALLEL_MAKE install