compile: add gnu-libstdc++ in EXTRA_LDFLAGS

cherry-picked from vlc-android (with configure.sh fix):

commit 69e0648c6a331cb7171ff1841a870809685b8ddd
Author: Thomas Guillem <thomas.guillem@gmail.com>
Date:   Wed Oct 1 18:42:06 2014 +0200

    Build: add gnu-libstdc++ in EXTRA_LDFLAGS

    fix protobuf build.

compile.sh

@@ -96,7 +96,7 @@ ANDROID_PATH="`pwd`"
 if [ ! -z "$FETCH" ]
 then
     # 1/ libsflphone
-    TESTED_HASH=00bf4e25091e03ced364b626e64bd92df038ab82
+    TESTED_HASH=c88b5559cfb36cca66b36d51166d02ae7c118d88
     if [ ! -d "sflphone" ]; then
         echo "sflphone daemon source not found, cloning"
         git clone https://gerrit-sflphone.savoirfairelinux.com/sflphone
@@ -170,6 +170,9 @@ EXTRA_CFLAGS="${EXTRA_CFLAGS} -I${ANDROID_NDK}/sources/cxx-stl/gnu-libstdc++${CX
 EXTRA_CFLAGS="${EXTRA_CFLAGS} -I${ANDROID_NDK}/sources/cxx-stl/gnu-libstdc++${CXXSTL}/libs/${ANDROID_ABI}/include"
 CXXFLAGS="${CXXFLAGS} -I/home/alision/sflphone-android/sflphone-android/jni"
 
+# Setup LDFLAGS
+EXTRA_LDFLAGS="-l${ANDROID_NDK}/sources/cxx-stl/gnu-libstdc++${CXXSTL}/libs/${ANDROID_ABI}/libgnustl_static.a"
+
 # Make in //
 UNAMES=$(uname -s)
 MAKEFLAGS=
@@ -217,7 +220,9 @@ else
 fi
 
 echo "EXTRA_CFLAGS= -g ${EXTRA_CFLAGS}" >> config.mak
+echo "EXTRA_LDFLAGS= ${EXTRA_LDFLAGS}" >> config.mak
 export SFLPHONE_EXTRA_CFLAGS="${EXTRA_CFLAGS}"
+export SFLPHONE_EXTRA_LDFLAGS="${EXTRA_LDFLAGS}"
 
 make install
 echo ${PWD}

configure.sh

@@ -43,7 +43,7 @@ cd $SFLPHONE_SOURCEDIR/daemon
 CPPFLAGS="$CPPFLAGS" \
 CFLAGS="$CFLAGS ${SFLPHONE_EXTRA_CFLAGS}" \
 CXXFLAGS="$CFLAGS" \
-LDFLAGS="$LDFLAGS" \
+LDFLAGS="$LDFLAGS ${SFLPHONE_EXTRA_LDFLAGS}" \
 CC="${CROSS_COMPILE}gcc --sysroot=${SYSROOT}" \
 CXX="${CROSS_COMPILE}g++ --sysroot=${SYSROOT}" \
 NM="${CROSS_COMPILE}nm" \