Correct all hits from

    git grep -e '\(&&\|||\)[^ ]' -e '[^	 ]\(&&\|||\)' -- '*.c'

i.e. && or || operators that are followed by anything but a SP,
or that follow something other than a SP or a HT, so that these
operators have a SP around it when necessary.

We usually refrain from making this kind of a tree-wide change in
order to avoid unnecessary conflicts with other "real work" patches,
but in this case, the end result does not have a potentially
cumbersome tree-wide impact, while this is a tree-wide cleanup.

Fixes to compat/regex/regcomp.c and xdiff/xemit.c are to replace a
HT immediately after && with a SP.

This is based on Felipe's patch to bultin/symbolic-ref.c; I did all
the finding out what other files in the whole tree need to be fixed
and did the fix and also the log message while reviewing that single
liner, so any screw-ups in this version are mine.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>