nfdump can not be compiled with ASLR PIE

Maintainer: @flyn-org
Environment: aarch64_cortex-a53 (Turris MOX), OpenWrt master
OpenWrt commit: 36e0268aa67bb757d7b9b39cbe1e7f89332f6746

Issue:

/bin/bash ../libtool  --tag=CC   --mode=link ccache_cc  -g -O3 -std=gnu11 -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wmissing-noreturn -fno-strict-aliasing  -L/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/usr/lib -L/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib -fPIC -specs=/foo/build/include/hardened-ld-pie.specs -znow -zrelro -Wl,--as-needed -lfts  -o nfcapd nfcapd-nfcapd.o nfcapd-nfstatfile.o nfcapd-launch.o nfcapd-nfnet.o nfcapd-collector.o nfcapd-netflow_v1.o nfcapd-netflow_v5_v7.o nfcapd-netflow_v9.o nfcapd-ipfix.o nfcapd-bookkeeper.o nfcapd-expire.o  -lnfdump  -lresolv -lbz2
OpenWrt-libtool: link: ccache_cc -g -O3 -std=gnu11 -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wmissing-noreturn -fno-strict-aliasing -fPIC -specs=/foo/build/include/hardened-ld-pie.specs -znow -zrelro -Wl,--as-needed -o .libs/nfcapd nfcapd-nfcapd.o nfcapd-nfstatfile.o nfcapd-launch.o nfcapd-nfnet.o nfcapd-collector.o nfcapd-netflow_v1.o nfcapd-netflow_v5_v7.o nfcapd-netflow_v9.o nfcapd-ipfix.o nfcapd-bookkeeper.o nfcapd-expire.o  -L/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/usr/lib -L/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib /foo/build/build_dir/target-aarch64_cortex-a53_musl/nfdump-1.6.22/bin/.libs/libnfdump.so -lfts -lresolv -lbz2
/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib/gcc/aarch64-openwrt-linux-musl/8.4.0/../../../../aarch64-openwrt-linux-musl/bin/ld: nfcapd-nfcapd.o: relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `optarg' which may bind externally can not be used when making a shared object; recompile with -fPIC
/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib/gcc/aarch64-openwrt-linux-musl/8.4.0/../../../../aarch64-openwrt-linux-musl/bin/ld: nfcapd-nfcapd.o(.text.startup+0x138): unresolvable R_AARCH64_ADR_PREL_PG_HI21 relocation against symbol `optarg'
/foo/build/staging_dir/toolchain-aarch64_cortex-a53_gcc-8.4.0_musl/lib/gcc/aarch64-openwrt-linux-musl/8.4.0/../../../../aarch64-openwrt-linux-musl/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

Start by reproducing the nfdump build on the stated aarch64 OpenWrt environment, focusing on the nfcapd link command and its generated object files. Trace why the nfcapd objects cannot be linked with the hardened-ld-pie.specs settings; done means nfdump compiles successfully with ASLR PIE enabled.