strvec: rename files from argv-array to strvec

This requires updating #include lines across the code-base, but that's
all fairly mechanical, and was done with:

  git ls-files '*.c' '*.h' |
  xargs perl -i -pe 's/argv-array.h/strvec.h/'

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

wt-status.c

@@ -8,7 +8,7 @@
 #include "diffcore.h"
 #include "quote.h"
 #include "run-command.h"
-#include "argv-array.h"
+#include "strvec.h"
 #include "remote.h"
 #include "refs.h"
 #include "submodule.h"