build-system: add script to build only libdivecomputer

This is used on LGTM (and initially got lost when I merged those changes).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

scripts/build-libdivecomputer.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+#
+# this should be run from the subsurface directory
+
+if [ ! -d libdivecomputer/src ] ; then
+	git submodule init
+	git submodule update --recursive
+fi
+
+mkdir -p libdivecomputer/build
+cd libdivecomputer/build
+
+if [ ! -f ../configure ] ; then
+	# this is not a typo
+	# in some scenarios it appears that autoreconf doesn't copy the
+	# ltmain.sh file; running it twice, however, fixes that problem
+	autoreconf --install ..
+	autoreconf --install ..
+fi
+
+../configure --disable-examples --prefix=$INSTALL_ROOT
+
+
+make -j4
+make install