android: build with clang instead of GCC

Attempt to fix "undefined reference to 'stdout' by
building with clang instead of GCC.

ref:
android/ndk#445 (comment)

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>

packaging/android/build.sh

@@ -148,8 +148,8 @@ export BUILDROOT=$PWD
 export PATH=${BUILDROOT}/ndk-$ARCH/bin:$PATH
 export PREFIX=${BUILDROOT}/ndk-$ARCH/sysroot/usr
 export PKG_CONFIG_LIBDIR=$PREFIX/lib/pkgconfig
-export CC=${BUILDROOT}/ndk-$ARCH/bin/${BUILDCHAIN}-gcc
-export CXX=${BUILDROOT}/ndk-$ARCH/bin/${BUILDCHAIN}-g++
+export CC=${BUILDROOT}/ndk-$ARCH/bin/${BUILDCHAIN}-clang
+export CXX=${BUILDROOT}/ndk-$ARCH/bin/${BUILDCHAIN}-clang++
 # autoconf seems to get lost without this
 export SYSROOT=${BUILDROOT}/ndk-$ARCH/sysroot
 export CFLAGS=--sysroot=${SYSROOT}