Fix bad string pointer arithmetic in condition reassert

On `initctl reload` we reassert conditions, i.e. bring each still viable
condition back in sync with the new reconf generation.  This patch fixes
an assumption in the reassert() callback that caused the following nasty
transformation:

	/run/finit/cond/net/lo/up --> /run/finit/cond/lo/up

The transformation was caused by the reassert() code assuming a /var/run
prefix rather than /run.  We must check the actual runpath, or like this
patch does, use a path neutral way to find the base condition string.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

src/cond-w.c

@@ -206,7 +206,13 @@ static int reassert(const char *fpath, const struct stat *sb, int tflg, struct F
 	if (tflg != FTW_F)
 		return 0;
 
-	nm = (char *)fpath + sizeof(COND_PATH);
+	nm = strstr((char *)fpath, COND_DIR);
+	if (!nm) {
+		_e("Incorrect condtion path %s, cannot reassert", fpath);
+		return 1;
+	}
+
+	nm += sizeof(COND_DIR) + 1;
 	_d("Reasserting %s => %s", fpath, nm);
 	cond_set(nm);