getopt32: factor out code to treat all args as options

Working towards making getopt32() xmalloc-free

function                                             old     new   delta
make_all_argv_opts                                     -      58     +58
top_main                                             914     912      -2
getopt32                                            1517    1458     -59
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 0/2 up/down: 58/-61)             Total: -3 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

libbb/getopt_allopts.c

@@ -0,0 +1,27 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Copyright (C) 2017 Denys Vlasenko
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+#include "libbb.h"
+
+//kbuild:lib-y += getopt_allopts.o
+
+void FAST_FUNC make_all_argv_opts(char **argv)
+{
+	/* Note: we skip argv[0] */
+	while (*++argv) {
+		char *p;
+
+		if (argv[0][0] == '-')
+			continue;
+		/* Neither top nor ps care if "" arg turns into "-" */
+		/*if (argv[0][0] == '\0')
+			continue;*/
+		p = xmalloc(strlen(*argv) + 2);
+		*p = '-';
+		strcpy(p + 1, *argv);
+		*argv = p;
+	}
+}