pcre2: fix host compilation of libselinux by enabling PIC

pcre2: fix host compilation of libselinux by enabling PIC

libselinux-3.5 fails to compile in Fedora 38 container due to the
following:

 cc -O2 -I/openwrt/staging_dir/host/include -I/openwrt/staging_dir/hostpkg/include -I/openwrt/staging_dir/target-x86_64_musl/host/include -I../include -D_GNU_SOURCE -DNO_ANDROID_BACKEND -DUSE_PCRE2 -DPCRE2_CODE_UNIT_WIDTH=8 -I/openwrt/staging_dir/hostpkg/include -L/openwrt/staging_dir/host/lib -L/openwrt/staging_dir/hostpkg/lib -L/openwrt/staging_dir/target-x86_64_musl/host/lib -Wl,-rpath=/openwrt/staging_dir/hostpkg/lib -shared -o libselinux.so.1 avc.lo avc_internal.lo avc_sidtab.lo booleans.lo callbacks.lo canonicalize_context.lo checkAccess.lo check_context.lo checkreqprot.lo compute_av.lo compute_create.lo compute_member.lo compute_relabel.lo compute_user.lo context.lo deny_unknown.lo disable.lo enabled.lo fgetfilecon.lo freecon.lo freeconary.lo fsetfilecon.lo get_context_list.lo get_default_type.lo get_initial_context.lo getenforce.lo getfilecon.lo getpeercon.lo init.lo is_customizable_type.lo label.lo label_db.lo label_file.lo label_media.lo label_support.lo label_x.lo lgetfilecon.lo load_policy.lo lsetfilecon.lo mapping.lo matchmediacon.lo matchpathcon.lo policyvers.lo procattr.lo query_user_context.lo regex.lo reject_unknown.lo selinux_check_securetty_context.lo selinux_config.lo selinux_internal.lo selinux_restorecon.lo sestatus.lo setenforce.lo setexecfilecon.lo setfilecon.lo setrans_client.lo seusers.lo sha1.lo stringrep.lo validatetrans.lo -L/openwrt/staging_dir/hostpkg/lib -lpcre2-8 -lfts -ldl -Wl,-soname,libselinux.so.1,--version-script=libselinux.map,-z,defs,-z,relro
 /usr/bin/ld: /openwrt/staging_dir/hostpkg/lib/libpcre2-8.a(pcre2_compile.c.o): relocation R_X86_64_32S against symbol `_pcre2_ucd_stage1_8' can not be used when making a shared object; recompile with -fPIC
 /usr/bin/ld: failed to set dynamic section sizes: bad value

So lets fix it by enabling build of host static library with the
position independent code option enabled.

Signed-off-by: Petr Štetiar <ynezz@true.cz>