dtksh: fix implicit-function-declaration warnings

Tis does not fix those warnings in ksh93 itself, only the stuff we are
responsible for.

cde/programs/dtksh/dtksh.h

@@ -153,5 +153,7 @@ typedef struct {
 	String verifyPrinterProcCommand;
 } ProcInfo_t;
 
+void dtksh_init(void);
+
 #endif /* _Dtksh_dtksh_h */
 /* DON'T ADD ANYTHING AFTER THIS #endif */

cde/programs/dtksh/xmcmds.c

@@ -99,6 +99,7 @@
 #include <Xm/ToggleB.h>
 #include <Xm/ToggleBG.h>
 
+#include <Dt/Dt.h>
 #include <Dt/HelpDialog.h>
 #include <Dt/HelpQuickD.h>
 #include <Dt/Print.h>