MSVC build fixes

hecl/lib/winsupport.c

@@ -0,0 +1,34 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+/*
+* The memmem() function finds the start of the first occurrence of the
+* substring 'needle' of length 'nlen' in the memory area 'haystack' of
+* length 'hlen'.
+*
+* The return value is a pointer to the beginning of the sub-string, or
+* NULL if the substring is not found.
+*/
+void *memmem(const uint8_t *haystack, size_t hlen, const void *needle, size_t nlen)
+{
+    int needle_first;
+    const uint8_t *p = haystack;
+    size_t plen = hlen;
+
+    if (!nlen)
+        return NULL;
+
+    needle_first = *(unsigned char *)needle;
+
+    while (plen >= nlen && (p = memchr(p, needle_first, plen - nlen + 1)))
+    {
+        if (!memcmp(p, needle, nlen))
+            return (void *)p;
+
+        p++;
+        plen = hlen - (p - haystack);
+    }
+
+    return NULL;
+}