libical: fix build failure after changing machine

libical: fix build failure after changing machine

libical build QA fails when libical is built for e.g. qemux86-64 already, and
is then built for generic86-64 in a way that install is re-run:

$ MACHINE=qemux86-64 bitbake libical
$ MACHINE=genericx86-64 bitbake -f -Cinstall libical

ERROR: libical-2.0.0-r0 do_populate_sysroot: QA Issue: libical.pc failed
sanity test (tmpdir) in path

[YOCTO #10223]

Signed-off-by: Maxin B. John <maxin.john@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>