libgnustl: Install as $PREFIX/lib/libstdc++.so

This will make C++ programs link to a working C++ library by
default, so that -lgnustl_shared no longer is necessary.

packages/libgnustl/build.sh

@@ -1,12 +1,16 @@
 TERMUX_PKG_HOMEPAGE=http://gcc.gnu.org/onlinedocs/libstdc++/
 TERMUX_PKG_DESCRIPTION="The GNU Standard C++ Library (a.k.a. libstdc++-v3), necessary on android since the system libstdc++.so is stripped down"
 TERMUX_PKG_VERSION=$TERMUX_NDK_VERSION
+TERMUX_PKG_BUILD_REVISION=1
 
-termux_step_extract_into_massagedir () {
-	mkdir -p $TERMUX_PKG_MASSAGEDIR/$TERMUX_PREFIX/lib/
+termux_step_make_install () {
         LIBFILE=$TERMUX_STANDALONE_TOOLCHAIN/${TERMUX_ARCH}-linux-android/lib/libgnustl_shared.so
         if [ $TERMUX_ARCH = arm ]; then
                 LIBFILE=$TERMUX_STANDALONE_TOOLCHAIN/arm-linux-androideabi/lib/armv7-a/hard/libgnustl_shared.so
         fi
-	cp $LIBFILE $TERMUX_PKG_MASSAGEDIR/$TERMUX_PREFIX/lib/
+
+	cp $LIBFILE $TERMUX_PREFIX/lib/
+	cd $TERMUX_PREFIX/lib/
+
+	ln -s -f libgnustl_shared.so libstdc++.so
 }