probe: fallback to libblkid.so.1 when libblkid.so does not exist

OpenWrt commit 0e70f69a35 ("treewide: revise library packaging") removed
the unversioned library symlink from the libblkid package, breaking
dynamic loading of the library at runtime.

Add a fallback to "libblkid.so.1" to allow using the dynamic library
for filesystem probing again.

Fixes: FS#2274
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

probe-libblkid.c

@@ -37,6 +37,9 @@ load_libblkid(void)
 	if (!libblkid.loaded) {
 		lib = dlopen("libblkid.so", RTLD_GLOBAL);
 
+		if (lib == NULL)
+			lib = dlopen("libblkid.so.1", RTLD_GLOBAL);
+
 		if (lib) {
 			libblkid.alloc  = dlsym(lib, "blkid_new_probe_from_filename");
 			libblkid.probe  = dlsym(lib, "blkid_do_probe");