[binutils-gdb] MIPS: Make `mask_address_var' static

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT ea33cd9290063d977fb2c31ea6a8567da585ab88 ***

Author: Maciej W. Rozycki <macro@mips.com>
Branch: master
Commit: ea33cd9290063d977fb2c31ea6a8567da585ab88

MIPS: Make `mask_address_var' static

Make the `mask_address_var' variable static, it is not used outside
mips-tdep.c and having no target name embedded within it causes a risk
of a namespace clash.

	gdb/
	* mips-tdep.c (mask_address_var): Make variable static.