rename superh port to "sh" for consistency

linux, gcc, etc. all use "sh" as the name for the superh arch. there
was already some inconsistency internally in musl: the dynamic linker
was searching for "ld-musl-sh.path" as its path file despite its own
name being "ld-musl-superh.so.1". there was some sentiment in both
directions as to how to resolve the inconsistency, but overall "sh"
was favored.

arch/sh/bits/shm.h

@@ -0,0 +1,28 @@
+#define SHMLBA 16384
+
+struct shmid_ds
+{
+	struct ipc_perm shm_perm;
+	size_t shm_segsz;
+	time_t shm_atime;
+	int __unused1;
+	time_t shm_dtime;
+	int __unused2;
+	time_t shm_ctime;
+	int __unused3;
+	pid_t shm_cpid;
+	pid_t shm_lpid;
+	unsigned long shm_nattch;
+	unsigned long __pad1;
+	unsigned long __pad2;
+};
+
+struct shminfo {
+	unsigned long shmmax, shmmin, shmmni, shmseg, shmall, __unused[4];
+};
+
+struct shm_info {
+	int __used_ids;
+	unsigned long shm_tot, shm_rss, shm_swp;
+	unsigned long __swap_attempts, __swap_successes;
+};