[binutils-gdb] Don't copy a string in mi_cmd_disassemble

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 9813429a729dbcd761dfbb02d2d7a3449af0881d ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: 9813429a729dbcd761dfbb02d2d7a3449af0881d

Don't copy a string in mi_cmd_disassemble

This string copy in mi_cmd_disassemble seems not to be needed, so
don't do it.

gdb/ChangeLog
2017-09-29  Tom Tromey  <tom@tromey.com>

	* mi/mi-cmd-disas.c (mi_cmd_disassemble): Don't copy "oarg".