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>
diff --git a/builtin/gc.c b/builtin/gc.c
index 8e0b9cf..27951ee 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -18,7 +18,7 @@
 #include "parse-options.h"
 #include "run-command.h"
 #include "sigchain.h"
-#include "argv-array.h"
+#include "strvec.h"
 #include "commit.h"
 #include "commit-graph.h"
 #include "packfile.h"