Update #include-related dependencies in Mamfiles

I grepped for #include changes in all the commits and compared
that to the changes in the Mamfiles. I found 7 commits that don't
update the Mamfiles with the appropriate dependencies while
adding #includes, as I only learned how this works after having
worked with this code for some time.

This commit adds the missing Mamfile updates for the
corresponding #include changes in the following commits:
06e721c3, 65d363fd, 70fc1da7, 79d19458, b1a41311, bb4d6a2e,
db71b3ad, and this commit.

Additionally:

src/lib/libast/comp/setlocale.c:
- Change include errno.h to error.h to use EILSEQ fallback if
  needed; remove corresponding #ifdef (re: 4dcf5c50, 71bfe028).

src/cmd/ksh93/Mamfile:
- Fix a broken dependency on libast FEATURE/float (re: 72968eae).
  We can't use 'prev' for a file that was not mentioned before in
  the same Mamfile, we have to use a 'make'...'done' on the first
  mention. Add subdependencies matching those in libast/Mamfile.

src/lib/libast/Mamfile

@@ -1099,6 +1099,7 @@ make install
 			done pathposix.o generated
 			make pathtemp.o
 				make path/pathtemp.c
+					prev include/error.h implicit
 					make include/tm.h implicit
 						prev include/times.h implicit
 						prev include/ast.h implicit
@@ -1472,6 +1473,7 @@ make install
 				make comp/setlocale.c
 					prev include/ast_windows.h implicit
 					prev std/wctype.h implicit
+					prev include/error.h implicit
 					prev include/namval.h implicit
 					make include/mc.h implicit
 						prev include/ast.h implicit
@@ -2559,6 +2561,7 @@ make install
 			make debug.o
 				make misc/debug.c
 					prev include/times.h implicit
+					prev FEATURE/time implicit
 					prev include/debug.h implicit
 					prev include/error.h implicit
 					prev include/ast.h implicit

src/lib/libast/comp/setlocale.c

@@ -36,7 +36,7 @@
 #include <ctype.h>
 #include <mc.h>
 #include <namval.h>
-#include <errno.h>
+#include <error.h>
 
 #if ( _lib_wcwidth || _lib_wctomb ) && _hdr_wctype
 #include <wctype.h>
@@ -633,9 +633,7 @@ utf8_mbtowc(wchar_t* wp, const char* str, size_t n)
 	if (!*sp)
 		return 0;
  invalid:
-#ifdef EILSEQ
 	errno = EILSEQ;
-#endif
 	ast.mb_sync = (const char*)sp - str;
 	return -1;
 }