remove unneeded error.h includes

These are the only two places where this glibc-specific
header is included. However none of the definitions in it
seem to be used, so just remove the includes.

src/notify/notify.c

@@ -21,7 +21,6 @@
 
 #include <stdio.h>
 #include <getopt.h>
-#include <error.h>
 #include <errno.h>
 #include <unistd.h>
 #include <stdlib.h>

src/path/path.c

@@ -21,7 +21,6 @@
 
 #include <stdio.h>
 #include <getopt.h>
-#include <error.h>
 #include <errno.h>
 #include <unistd.h>
 #include <stdlib.h>