libobs: Add wstrstri function

Performs a case-insensitive search for a wide-character string within
another wide-character string.

libobs/util/dstr.c

@@ -179,6 +179,23 @@ char *astrstri(const char *str, const char *find)
 	return NULL;
 }
 
+wchar_t *wstrstri(const wchar_t *str, const wchar_t *find)
+{
+	size_t len;
+
+	if (!str || !find)
+		return NULL;
+
+	len = wcslen(find);
+
+	do {
+		if (wstrcmpi_n(str, find, len) == 0)
+			return (wchar_t*)str;
+	} while (*str++);
+
+	return NULL;
+}
+
 char *strdepad(char *str)
 {
 	char *temp;

libobs/util/dstr.h

@@ -47,6 +47,7 @@ EXPORT int astrcmpi_n(const char *str1, const char *str2, size_t n);
 EXPORT int wstrcmpi_n(const wchar_t *str1, const wchar_t *str2, size_t n);
 
 EXPORT char *astrstri(const char *str, const char *find);
+EXPORT wchar_t *wstrstri(const wchar_t *str, const wchar_t *find);
 
 EXPORT char *strdepad(char *str);
 EXPORT wchar_t *wcsdepad(wchar_t *str);