package/kodi: Fix linking with sunxi-mali

Since
http://git.buildroot.net/buildroot/commit/package/sunxi-mali?id=8906f272ab41e0373f392cc7a04cc97320dd8382
sunxi-mali as egl/gles provider also depends on libump.

This dependency was unknown to Kodi leading to this error during
configure:

configure:23127: /home/buildroot/build/instance-0/output/host/usr/bin/arm-none-linux-gnueabi-gcc -o conftest -O2 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64   -Os  -fPIC -DPIC -D_REENTRANT -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -g -D_DEBUG -Wall -mno-apcs-stack-check -mfpu=neon -mvectorize-with-neon-quad -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  conftest.c -lEGL   -lpython2.7 -lpthread -ldl -lutil -lm >&5
/home/buildroot/build/instance-0/output/host/opt/ext-toolchain/bin/../lib/gcc/arm-none-linux-gnueabi/4.8.3/../../../../arm-none-linux-gnueabi/bin/ld: warning: libUMP.so.2, needed by /home/buildroot/build/instance-0/output/host/usr/arm-buildroot-linux-gnueabi/sysroot/thumb2/usr/lib/libMali.so, not found (try using -rpath or -rpath-link)
/home/buildroot/build/instance-0/output/host/usr/arm-buildroot-linux-gnueabi/sysroot/thumb2/usr/lib/libEGL.so: undefined reference to `ump_close'

This patch updates CXXFLAGS with the necessary libs to fix linking of
the final kodi binary. The additional CFLAGS are needed because
configure uses gcc to detect egl support.

Fixes
http://autobuild.buildroot.net/results/ce3/ce35d25253410abcbdbf1c58a5c9fb90f4eea6cd/
http://autobuild.buildroot.net/results/1ee/1eefd8e23d8e1b4374c79201b4c631603372d431/
http://autobuild.buildroot.net/results/3d8/3d8314392c61d6d278fb900a028e3bfc4d1d4d2c/
http://autobuild.buildroot.net/results/ee5/ee5e53ed9e2bbebab64122dd422d5da6abca3095/
http://autobuild.buildroot.net/results/703/7033594221b4a75e7f8aea8c145c8b7d2db0637c/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>