libcap: fix -native and usrmerge builds

When attempting to build a -native package which DEPENDS on
libcap-native the libcap libraries are not found and the build will
fail (for example attempting to build qemu-native with
'PACKAGECONFIG_append = " virtfs"').

It turns out commit 2c9c4a406a [libcap: fix (base_)libdir usage]
breaks builds of libcap(-native) when $root_prefix is not "". This is
because the variables which define $root_prefix are also part of
$prefix so you end up with part of the path being used twice, first as
part of 'lib=' in do_compile, and secondly as part of 'prefix=' in
do_install. When $root_prefix is "" this isn't noticed.

By using $baselib we should not re-break the issue which commit
2c9c4a406a was fixing but we should avoid doubling down on the
paths thus fixing the -native and usrmerge builds.

(From OE-Core rev: b46c55c3b9db5d8f2080ae2611294a5b24efe4a4)

Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/libcap/libcap_2.25.bb

@@ -32,7 +32,7 @@ PACKAGECONFIG[pam] = "PAM_CAP=yes,PAM_CAP=no,libpam"
 
 EXTRA_OEMAKE = " \
   INDENT=  \
-  lib='${base_libdir}' \
+  lib='${baselib}' \
   RAISE_SETFCAP=no \
   DYNAMIC=yes \
   BUILD_GPERF=yes \