Fix various minor problems and update the documentation (#237)

These are minor fixes I've accumulated over time. The following
changes are somewhat notable:

- Added a missing entry for 'typeset -s' to the man page.
- Add strftime(3) to the 'see also' section. This and the date(1)
  addition are meant to add onto the documentation for 'printf %T'.
- Removed the man page the entry for ksh reading $PWD/.profile on
  login. That feature was removed in commit aa7713c2.
- Added date(1) to the 'see also' section of the man page.
- Note that the 'hash' command can be used instead of 'alias -t' to
  workaround one of the caveats listed in the man page.
- Use an 'out of memory' error message rather than 'out of space'
  when memory allocation fails.
- Replaced backticks with quotes in some places for consistency.
- Added missing documentation for the %P date format.
- Added missing documentation for the printf %Q and %p formats
  (backported from ksh2020: https://github.com/att/ast/pull/1032).
- The comments that show each builtin's options have been updated.

src/lib/libast/sfio/sfdisc.c

@@ -30,7 +30,7 @@
 **	consideration is stacking a discipline onto a read stream. Each
 **	discipline operation implies buffer synchronization so the stream
 **	buffer should be empty. However, a read stream representing an
-**	unseekable device (eg, a pipe) may not be synchronizable. In that
+**	unseekable device (e.g., a pipe) may not be synchronizable. In that
 **	case, any buffered data must then be fed to the new discipline
 **	to preserve data processing semantics. This is done by creating
 **	a temporary discipline to cache such buffered data and feed

src/lib/libast/sfio/sfpkrd.c

@@ -54,7 +54,7 @@ size_t	n;	/* buffer size */
 int	rc;	/* record character */
 long	tm;	/* time-out */
 int	action;	/* >0: peeking, if rc>=0, get action records,
-		   <0: no peeking, if rc>=0, get -action records,
+		   <0: no peeking, if rc>=0, get action records,
 		   =0: no peeking, if rc>=0, must get a single record
 		   =2: same as >0, but always use select(2)
 		*/
@@ -107,12 +107,12 @@ int	action;	/* >0: peeking, if rc>=0, get action records,
 					break;
 			}
 		}
-#endif /* stream_peek */
+#endif /* _stream_peek */
 
 		if(ntry == 1)
 			break;
 
-		/* poll or select to see if data is present.  */
+		/* use select to see if data is present */
 		while(tm >= 0 || action > 0 ||
 			/* block until there is data before peeking again */
 			((t&STREAM_PEEK) && rc >= 0) ||

src/lib/libast/sfio/sfpoll.c

@@ -34,7 +34,7 @@ int sfpoll(Sfio_t** fa, reg int n, int tm)
 int sfpoll(fa, n, tm)
 Sfio_t**	fa;	/* array of streams to poll		*/
 reg int		n;	/* number of streams in array		*/
-int		tm;	/* time in millisecs for select/poll	*/
+int		tm;	/* time in milliseconds for select/poll	*/
 #endif
 {
 	reg int		r, c, m, np, eintr;

src/lib/libast/sfio/sfseek.c

@@ -203,7 +203,7 @@ int	type;	/* 0: from org, 1: from here, 2: from end */
 
 #ifdef MAP_TYPE
 	if(f->bits&SF_MMAP)
-	{	/* if mmap is not great, stop mmaping if moving around too much */
+	{	/* if mmap is not great, stop mmapping if moving around too much */
 #if _mmap_worthy < 2
 		if((f->next - f->data) < ((f->endb - f->data)/4) )
 		{	SFSETBUF(f,(Void_t*)f->tiny,(size_t)SF_UNBOUND);

src/lib/libast/sfio/sfsetbuf.c

@@ -410,7 +410,7 @@ done:
 	_Sfi = f->val = obuf ? osize : 0;
 
 	/* blksz is used for aligning disk block boundary while reading data to
-	** optimize data transfer from disk (eg, via direct I/O). blksz can be
+	** optimize data transfer from disk (e.g., via direct I/O). blksz can be
 	** at most f->size/2 so that data movement in buffer can be optimized.
 	** blksz should also be a power-of-2 for optimal disk seeks.
 	*/

src/lib/libast/sfio/sftmp.c

@@ -218,7 +218,7 @@ Sfio_t*	f;
 # if defined(__linux__) && _lib_statfs
 	/*
 	 * Use the area of POSIX shared memory objects for the new temporary file descriptor
-	 * that is do not access HD or SSD but only the memory based tmpfs of the POSIX SHM
+	 * that is do not access the HDD or SSD but only the memory based tmpfs of the POSIX SHM
 	 */
 	static int doshm;
 	static char *shm = "/dev/shm";