package/oprofile: fix static linking

When getext is enabled, popt links with -lintl, specifies it in its
popt.pc and has done so for the past 6+ years. But oprofile does not
use pkconfig to find popt, so misses -lintl, which is important for
a static build. We have to do the call to pkgconfig manually...

Fixes:
    http://autobuild.buildroot.org/results/a48/a485f2171a3fcbfa2e0e5aec8e653cf88512615d/
    http://autobuild.buildroot.org/results/b37/b374874f1915ab1d7aa6262604ccc8db102bb0b0/
    http://autobuild.buildroot.org/results/261/2616a63081ed8c55c7ca1a6879b1a6a14e19f918/
    http://autobuild.buildroot.org/results/73f/73f34ab59d54ded68ff60608a0212a6e5a5190e5/


    ...

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>