Fix sanitary_path_copy() for absolute Windows style paths.

We recognized the drive letter and colon, but we did not copy them. So far
this was not a problem since the only call site used the same pointer for
source and destination. But better safe than sorry.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>

setup.c

@@ -16,9 +16,9 @@ static int sanitary_path_copy(char *dst, const char *src)
 
 #ifdef __MINGW32__
 	if (isalpha(*src) && src[1] == ':') {
-		src += 2;
-		dst += 2;
-		dst0 += 2;
+		*dst++ = *src++;
+		*dst++ = *src++;
+		dst0 = dst;
 	}
 #endif
 	if (is_dir_sep(*src)) {