gdb/aarch64: Tests for fpmr Add tests for FPMR support in gdb/gdbserver. These tests check availability of FPMR, reading/writing to FPMR, core file generation and preservation under sighandler frame unwinding. A run of the full gdb testsuite has been done on aarch64-none-linux-gnu without FPMR support. The gdb.arch tests were run on Shrinkwrap with FPMR support. Approved-By: Luis Machado <luis.machado.foss@gmail.com>