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/float.h

@@ -0,0 +1,17 @@
+#define FLT_ROUNDS 1
+#define FLT_EVAL_METHOD 0
+
+#define LDBL_TRUE_MIN 4.94065645841246544177e-324L
+#define LDBL_MIN 2.22507385850720138309e-308L
+#define LDBL_MAX 1.79769313486231570815e+308L
+#define LDBL_EPSILON 2.22044604925031308085e-16L
+
+#define LDBL_MANT_DIG 53
+#define LDBL_MIN_EXP (-1021)
+#define LDBL_MAX_EXP 1024
+
+#define LDBL_DIG 15
+#define LDBL_MIN_10_EXP (-307)
+#define LDBL_MAX_10_EXP 308
+
+#define DECIMAL_DIG 17