Add missing major() and minor().

Based on glibc version of this functions. Parted relies on those
functions and they're not provided by bionic libc.

diff -ur src-orig/libparted/arch/linux.c src/libparted/arch/linux.c
--- src-orig/libparted/arch/linux.c	2017-08-31 15:47:07.007674598 +0200
+++ src/libparted/arch/linux.c	2017-08-31 15:50:01.487860337 +0200
@@ -86,6 +86,22 @@
 #define WR_MODE (O_WRONLY)
 #define RW_MODE (O_RDWR)
 
+unsigned int major(dev_t __dev)
+{
+	unsigned int __major;
+	__major  = ((__dev & (dev_t) 0x00000000000fff00u) >>  8);
+	__major |= ((__dev & (dev_t) 0xfffff00000000000u) >> 32);
+	return __major;
+}
+
+unsigned int minor(dev_t __dev)
+{
+	unsigned int __minor;
+	__minor  = ((__dev & (dev_t) 0x00000000000000ffu) >>  0);
+	__minor |= ((__dev & (dev_t) 0x00000ffffff00000u) >> 12);
+	return __minor;
+}
+
 struct hd_geometry {
         unsigned char heads;
         unsigned char sectors;