git.c: remove excess output for debugging when command is too long.

git.c: remove excess output for debugging when command is too long.

When the given command name was too long, we exited with a
message with the number of bytes of the final command name
inside parentheses, without saying what that number is.  It was
only meant as a debugging aid while development, so remove it.

Signed-off-by: Junio C Hamano <junkio@cox.net>