add compat getopt implementation, remove patches

This adds a getopt implementation for compatibility where it is not
available, removing a couple of regress patches.

Note, this is a slightly modified copy from OpenBSD libc that doesn't
expose getopt_long, which has dependency conflicts with Windows system
headers and isn't needed anyway.

patches/bn_isqrt.c.patch

@@ -1,18 +0,0 @@
---- tests/bn_isqrt.c.orig	Fri Dec  9 11:05:26 2022
-+++ tests/bn_isqrt.c	Fri Dec  9 11:12:37 2022
-@@ -306,6 +306,7 @@ main(int argc, char *argv[])
- 	int ch;
- 	int failed = 0, print = 0;
- 
-+#ifndef _MSC_VER
- 	while ((ch = getopt(argc, argv, "C")) != -1) {
- 		switch (ch) {
- 		case 'C':
-@@ -316,6 +317,7 @@ main(int argc, char *argv[])
- 			break;
- 		}
- 	}
-+#endif
- 
- 	if (print)
- 		return check_tables(1);

patches/handshake_table.c.patch

@@ -1,18 +0,0 @@
---- tests/handshake_table.c.orig	Tue Mar 15 11:37:03 2022
-+++ tests/handshake_table.c	Mon Mar 21 05:26:15 2022
-@@ -518,6 +518,7 @@
- 	unsigned int	depth = 0;
- 	int		ch, graphviz = 0, print = 0;
- 
-+#ifndef _MSC_VER
- 	while ((ch = getopt(argc, argv, "Cg")) != -1) {
- 		switch (ch) {
- 		case 'C':
-@@ -535,6 +536,7 @@
- 
- 	if (argc != 0)
- 		usage();
-+#endif
- 
- 	if (graphviz && print)
- 		usage();