fix 5 more typos: incorrect "than"

(cherry picked from commit 7e2e4651d2dd5884dd3ea06fc8df4dc45ec9bfb5)

src/cmd/ksh93/nval.3

@@ -162,7 +162,7 @@ Otherwise, if \f5NV_ASSIGN\fP is specified, then the characters up
 to the first \f5=\fP or \f5+=\fP are used to find the name-value pair,
 and the characters after the \f5=\fP are used to define
 the value that will be assigned to this name-value pair.
-If \fIname\fP does not contain an \f5=\fP, than no assignment
+If \fIname\fP does not contain an \f5=\fP, then no assignment
 will be made.
 If the first identifier in \fIname\fP is a reference and is not
 preceded by a \fB.\fP,

src/cmd/ksh93/sh/macro.c

@@ -155,7 +155,7 @@ char *sh_mactry(Shell_t *shp,register char *string)
  * expansion on <str>. 
  * If <mode> greater than 1 file expansion is performed if the result 
  * yields a single pathname.
- * If <mode> negative, than expansion rules for assignment are applied.
+ * If <mode> negative, then expansion rules for assignment are applied.
  */
 char *sh_mactrim(Shell_t *shp, char *str, register int mode)
 {

src/cmd/ksh93/tests/shtests

@@ -43,8 +43,8 @@ USAGE=$'
     script names matching \b'$timesensitive$'\b are run with
     \bVMALLOC_OPTIONS\b unset.]
 [V:valgrind?Set \b--novmalloc_options\b and run the test scripts with
-    \bvalgrind\b(1) on \bksh\b. If \b$SHELL-g\b exists and is executable
-    than it is used instead of \b$SHELL\b.]
+    \bvalgrind\b(1) on \bksh\b. If \b$SHELL-g\b exists and is executable,
+    then it is used instead of \b$SHELL\b.]
 [x:trace?Enable script execution trace.]
 
 [ test.sh ... ] [ name=value ... ]