Fix(?) more Windows warnings.

src/conio/curs_cio.c

@@ -111,7 +111,7 @@ static int _putch(unsigned char ch, BOOL refresh_now, int cp)
 	cchar_t	cha;
 	wchar_t wch[2] = {0};
 	attr_t	attr = 0;
-	short	cpair;
+	short	cpair = 0;
 
 	attr_get(&attr, &cpair, NULL);
 	attr &= ~A_COLOR;

src/conio/scale.c

+#include <math.h>
 #include <stdbool.h>
 #include <stdlib.h>
 

src/conio/x_events.c

@@ -3,6 +3,7 @@
  * event thread.
  */
  
+#include <math.h>
 #include <unistd.h>
 #include <stdbool.h>
 

src/syncterm/bbslist.c

@@ -7,6 +7,7 @@
 #include <dirwrap.h>
 #include <ini_file.h>
 #include <uifc.h>
+#include <xpprintf.h>
 #include "filepick.h"
 
 #include "syncterm.h"

src/syncterm/ripper.c

@@ -23,6 +23,7 @@
 #if defined(__unix__)
 	#include <unistd.h>
 #endif
+#include <time.h>
 #include <vidmodes.h>
 #include <xpbeep.h>

src/xpdev/strwrap.h

@@ -18,7 +18,7 @@ char* ltoa(long val, char* str, int radix);
 
 #endif
 
-#ifdef _MSVC
+#if defined(_MSC_VER) || defined(__MSVCRT__)
 #if defined(__cplusplus)
 extern "C" {
 #endif