play-audio: Fix shared library clash

The play-audio binary links to libOpenSLES, which links indirectly
to libskia. As libskia links to both libpng and libjpeg this means
problems if either of those libraries are installed from a Termux
package into LD_LIBRARY_PATH.

Avoid this by placing the play-audio binary into libexec/, and let
bin/play-audio be a wrapper script which resets LD_LIBRARY_PATH
before calling the binary in libexec/. Fixes #103.

packages/play-audio/build.sh

@@ -1,12 +1,16 @@
 TERMUX_PKG_HOMEPAGE=http://termux.com
 TERMUX_PKG_DESCRIPTION="Simple commandline audio player for Android"
-TERMUX_PKG_VERSION=0.2
+TERMUX_PKG_VERSION=0.3
 
 termux_step_make_install () {
+	local LIBEXEC_BINARY=$TERMUX_PREFIX/libexec/play-audio
 	$CXX $CFLAGS $LDFLAGS \
 		-std=c++14 -Wall -Wextra -pedantic -Werror \
 		-lOpenSLES \
-		$TERMUX_PKG_BUILDER_DIR/play-audio.cpp -o $TERMUX_PREFIX/bin/play-audio
+		$TERMUX_PKG_BUILDER_DIR/play-audio.cpp -o $LIBEXEC_BINARY
+
+	printf "#!/bin/sh\n\n# Avoid linker errors due to libOpenSLES.so:\nLD_LIBRARY_PATH= exec $LIBEXEC_BINARY \$@\n" > $TERMUX_PREFIX/bin/play-audio
+	chmod +x $TERMUX_PREFIX/bin/play-audio
 
 	mkdir -p $TERMUX_PREFIX/share/man/man1/
 	cp $TERMUX_PKG_BUILDER_DIR/play-audio.1 $TERMUX_PREFIX/share/man/man1/