ndk-sysroot: Setup librt&libpthread symlinks

The librt and libpthread libraries are built into libc on Android
and does not exist as separate libraries.

We now set them up as symlinks to libc for compatibility.

Fixes #403.

build-package.sh

@@ -555,8 +555,10 @@ termux_step_massage () {
 	# .. move over sbin to bin
 	for file in sbin/*; do if test -f $file; then mv $file bin/; fi; done
 
-        # Remove world permissions and add write permissions:
-        find . -exec chmod u+w,o-rwx \{\} \;
+        # Remove world permissions and add write permissions.
+	# The -f flag is used to suppress warnings about dangling symlinks (such
+	# as ones to /system/... which may not exist on the build machine):
+        find . -exec chmod -f u+w,o-rwx \{\} \;
 	if [ "$TERMUX_DEBUG" = "" ]; then
 		# Strip binaries. file(1) may fail for certain unusual files, so disable pipefail.
 		set +e +o pipefail

packages/ndk-sysroot/build.sh

@@ -1,7 +1,7 @@
 TERMUX_PKG_HOMEPAGE=https://developer.android.com/tools/sdk/ndk/index.html
 TERMUX_PKG_DESCRIPTION="System header and library files from the Android NDK needed for compiling C programs"
 TERMUX_PKG_VERSION=$TERMUX_NDK_VERSION
-TERMUX_PKG_BUILD_REVISION=3
+TERMUX_PKG_BUILD_REVISION=4
 TERMUX_PKG_NO_DEVELSPLIT=yes
 # Depend on libandroid-support-dev so that iconv.h and libintl.h are available:
 TERMUX_PKG_DEPENDS="libandroid-support-dev"
@@ -24,4 +24,13 @@ Requires:
 Libs: -L$TERMUX_PREFIX/lib -lz
 Cflags: -I$TERMUX_PREFIX/include
 HERE
+
+	# librt and libpthread are built into libc on android, so setup them as symlinks
+	# to libc for compatibility with programs that users try to build:
+	local _SYSTEM_LIBDIR=/system/lib64
+	if [ $TERMUX_ARCH_BITS = 32 ]; then _SYSTEM_LIBDIR=/system/lib; fi
+	mkdir -p $TERMUX_PKG_MASSAGEDIR/$TERMUX_PREFIX/lib
+	cd $TERMUX_PKG_MASSAGEDIR/$TERMUX_PREFIX/lib
+	ln -f -s $_SYSTEM_LIBDIR/libc.so librt.so
+	ln -f -s $_SYSTEM_LIBDIR/libc.so libpthread.so
 }