patch 8.2.0793: MS-Windows: cannot build GUI with small features

Problem:    MS-Windows: cannot build GUI with small features. (Michael Soyka)
Solution:   Add #ifdef around use of windowsVersion. (Ken Takata)
diff --git a/src/os_win32.c b/src/os_win32.c
index edd5cda..89c7c5e 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -822,7 +822,7 @@
 #endif
 
 /*
- * Set "win8_or_later" and fill in "windowsVersion".
+ * Set "win8_or_later" and fill in "windowsVersion" if possible.
  */
     void
 PlatformId(void)
@@ -836,9 +836,10 @@
 	ovi.dwOSVersionInfoSize = sizeof(ovi);
 	GetVersionEx(&ovi);
 
+#ifdef FEAT_EVAL
 	vim_snprintf(windowsVersion, sizeof(windowsVersion), "%d.%d",
 		(int)ovi.dwMajorVersion, (int)ovi.dwMinorVersion);
-
+#endif
 	if ((ovi.dwMajorVersion == 6 && ovi.dwMinorVersion >= 2)
 		|| ovi.dwMajorVersion > 6)
 	    win8_or_later = TRUE;
diff --git a/src/version.c b/src/version.c
index 14eca5f..055a418 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    793,
+/**/
     792,
 /**/
     791,