define NO_DOT_IN_LABEL only in vxworks6

define NO_DOT_IN_LABEL only in vxworks6

There was a mistake in forward-porting and contributing some
vxworks7r2 changes, that caused a conditional to be dropped around a
couple of preprocessor directives, needed only up to vxworks6, that
change the compiler's behavior WRT introducing dollars and dots in
symbol names.

This deviates GCC's behavior from the native system compiler, in a way
that appears to have ABI implications, so we'd like to correct that,
even at this late stage in the development cycle.

for  gcc/ChangeLog

	* config/vx-common.h (NO_DOLLAR_IN_LABEL, NO_DOT_IN_LABEL): Leave
	them alone on vx7.