seeks: fix compile on platforms with VFP

seeks: fix compile on platforms with VFP

This solution might be a little bit dirty - is adding those -mfloat-abi
switches to CXXFLAGS in rules.mk cleaner ?
but they are overwritten in this case so dunno :/

reported by buildbot on sunxi

configure fails to detect C++ compiler:
a.out uses VFP register arguments, /tmp/ccHPrqts.o does not
fixed by first change

other errors when linking:
ld: error: .libs/libseeksutils.so.0.0.0 uses VFP register arguments, .libs/miscutil.o does not
ld: error: .libs/libseeksutils.so.0.0.0 uses VFP register arguments, .libs/mem_utils.o does not
ld: error: .libs/libseeksutils.so.0.0.0 uses VFP register arguments, .libs/mutexes.o does not
fixed by second change

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
git-svn-id: svn://svn.openwrt.org/openwrt/packages@40724 3c298f89-4303-0410-b956-a3cf2f4a3e73