[CF] TARGET_OS_BSD for FS representation behavior.

CFURLGetFileSystemRepresentation's implementation has TARGET_OS_MAC and
TARGET_OS_LINUX, but not TARGET_OS_BSD. Nothing here appears macOS or
Linux specific, and things seem to work okay with TARGET_OS_BSD, so
enable it here too.

This also requires CanonicalFileURLStringToFileSystemRepresentation to
be exposed.

Author: 3405691582

CoreFoundation/URL.subproj/CFURL.c

@@ -4064,7 +4064,7 @@ static CFStringRef URLPathToPOSIXPath(CFStringRef path, CFAllocatorRef allocator
     return result;
 }
 
-#if TARGET_OS_MAC || TARGET_OS_LINUX
+#if TARGET_OS_MAC || TARGET_OS_LINUX || TARGET_OS_BSD
 static Boolean CanonicalFileURLStringToFileSystemRepresentation(CFStringRef str, UInt8 *inBuffer, CFIndex inBufferLen)
 {
     size_t fileURLPrefixLength;
@@ -4534,13 +4534,12 @@ CFStringRef CFURLCreateStringWithFileSystemPath(CFAllocatorRef allocator, CFURLR
 }
 
 Boolean CFURLGetFileSystemRepresentation(CFURLRef url, Boolean resolveAgainstBase, uint8_t *buffer, CFIndex bufLen) {
-#if TARGET_OS_MAC || TARGET_OS_LINUX || TARGET_OS_WIN32
     CFAllocatorRef alloc = CFGetAllocator(url);
     CFStringRef path;
 
     if (!url) return false;
-#endif
-#if TARGET_OS_MAC || TARGET_OS_LINUX
+
+#if TARGET_OS_MAC || TARGET_OS_LINUX || TARGET_OS_BSD
     if ( !resolveAgainstBase || (CFURLGetBaseURL(url) == NULL) ) {
         if (!CF_IS_OBJC(CFURLGetTypeID(), url)) {
             // We can access the ivars