SHOPT_MULTIBYTE-related cleanup (re: 8477d2ce)

As of 8477d2ce, the mbwide() macro (which tests if we're in a
multibyte locale, i.e. UTF-8) is redefined as a constant 0 if we're
compiling without SHOPT_MULTIBYTE. See src/cmd/ksh93/include/defs.h

The other multibyte macros use mbwide() as well, so they all revert
to the single-byte fallbacks in that case, and the multibyte code
in them is never compiled. See src/lib/libast/include/ast.h

Consequently we can now do a bit of cleanup and get rid of many of
the '#if SHOPT_MULTIBYTE' directives, as the compiler optimiser
will happily remove the multibyte-specific code. This increases the
legibility of the ksh code.

I'm taking the opportunity to fix a few typos and whitespace
formatting glitches as well.

src/cmd/ksh93/edit/completion.c

@@ -31,10 +31,6 @@
 #include	"edit.h"
 #include	"history.h"
 
-#if !SHOPT_MULTIBYTE
-#define mbchar(p)       (*(unsigned char*)p++)
-#endif
-
 static char *fmtx(const char *string)
 {
 	register const char	*cp = string;

src/cmd/ksh93/edit/history.c

@@ -1013,9 +1013,7 @@ int hist_match(register History_t *hp,off_t offset,char *string,int *coffset)
 {
 	register unsigned char *first, *cp;
 	register int m,n,c=1,line=0;
-#if SHOPT_MULTIBYTE
 	mbinit();
-#endif /* SHOPT_MULTIBYTE */
 	sfseek(hp->histfp,offset,SEEK_SET);
 	if(!(cp = first = (unsigned char*)sfgetr(hp->histfp,0,0)))
 		return(-1);
@@ -1033,10 +1031,8 @@ int hist_match(register History_t *hp,off_t offset,char *string,int *coffset)
 			break;
 		if(*cp=='\n')
 			line++;
-#if SHOPT_MULTIBYTE
 		if((c=mbsize(cp)) < 0)
 			c = 1;
-#endif /* SHOPT_MULTIBYTE */
 		cp += c;
 		m -= c;
 	}