Use semicolon as a directory delimiter on Windows
Windows path names have ':' inside as a drive letter separator. The
widespread convention on that platform is to use ';' as a list separator
in file paths, so let's follow suite.
It looks like this multi-value searchdir is only used in `ly_ctx_new()`,
and that all other functions operate on one directory at a time.
diff --git a/src/common.h b/src/common.h
index 4430962..7e80b1e 100644
--- a/src/common.h
+++ b/src/common.h
@@ -629,4 +629,10 @@
*/
LY_ERR ly_strcat(char **dest, const char *format, ...);
+#ifndef _WIN32
+# define PATH_SEPARATOR ":"
+#else
+# define PATH_SEPARATOR ";"
+#endif
+
#endif /* LY_COMMON_H_ */