get rid of XFree86LOADER, XFree86Server, XFree86Module, and IN_MODULE

Get rid of almost all uses of these definitions.  They're still defined for
delinquent out-of-tree drivers, and also for the Mesa build.  As well as
for miinitext.c.  But largely gone.

include/os.h

@@ -88,12 +88,8 @@ typedef struct _NewClientRec *NewClientPtr;
 #define xnfstrdup(s) XNFstrdup(s)
 #endif
 
-#ifndef IN_MODULE
-#ifdef __SCO__
 #include <stdio.h>
-#endif
-#include <string.h>
-#endif
+#include <stdarg.h>
 
 /* have to put $(SIGNAL_DEFINES) in DEFINES in Imakefile to get this right */
 #ifdef SIGNALRETURNSINT
@@ -517,10 +513,4 @@ extern void ErrorF(const char *f, ...) _printf_attribute(1,2);
 extern void Error(char *str);
 extern void LogPrintMarkers(void);
 
-#if defined(NEED_SNPRINTF) && !defined(IN_MODULE)
-extern int snprintf(char *str, size_t size, const char *format, ...)
-	_printf_attribute(3,4);
-extern int vsnprintf(char *str, size_t size, const char *format, va_list ap);
-#endif
-
 #endif /* OS_H */