Check whether symbols with MOVW_.ABS relocations require PLT entries (aarch64).

Check whether symbols with MOVW_.ABS relocations require PLT entries (aarch64).

2019-02-19  Egeyar Bagcioglu  <egeyar.bagcioglu@oracle.com>

gold/
     PR gold/23870
     * aarch64.cc (Target_aarch64::Scan::global): Check if a symbol with
     R_AARCH64_MOVW_.ABS_* relocations requires a PLT entry.
     * testsuite/Makefile.am: Add aarch64_pr23870 test case.
     * testsuite/Makefile.in: Regenerate.
     * testsuite/aarch64_pr23870_bar.c: New file.
     * testsuite/aarch64_pr23870_foo.c: New file.
     * testsuite/aarch64_pr23870_main.S: New file.