This patch fixes an assertion failure on long system register operands
in the AArch64 backend. See the new testcase for an input which
reproduces the issue.
gas/ChangeLog:
* config/tc-aarch64.c (parse_sys_reg): Don't assert when parsing
a long system register.
(parse_sys_ins_reg): Likewise.
(sysreg_hash_insert): New.
(md_begin): Use sysreg_hash_insert() to ensure all system
registers are no longer than the maximum length at startup.
* testsuite/gas/aarch64/invalid-sysreg-assert.d: New test.
* testsuite/gas/aarch64/invalid-sysreg-assert.l: Error output.
* testsuite/gas/aarch64/invalid-sysreg-assert.s: Input.