i#2356 sigcontext types: Replace tab characters with spaces in "sigcontext.h". (#2419)
i#2356 sigcontext types: Replace tab characters with spaces in "sigcontext.h". (#2419)

Replaces tabs with spaces in DR's copy of sigcontext.h.
AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio