#366 Support quiet uninstalls

[Anders]

7-Zip should write the QuietUninstallString uninstall entry so WinGet and other tools can do silent uninstalls.

--- old\7zipInstall.c   Wed Sep 01 21:11:02 2021
+++ new\7zipInstall.c   Wed Sep 01 21:12:47 2021
@@ -926,7 +926,9 @@
       wcscpy(destPath + 1, path);
       CatAscii(destPath, "Uninstall.exe\"");
       MyRegistry_SetString(destKey, L"UninstallString", destPath);
-      
+      CatAscii(destPath, " /S");
+      MyRegistry_SetString(destKey, L"QuietUninstallString", destPath);
+
       MyRegistry_SetDWORD(destKey, L"NoModify", 1);
       MyRegistry_SetDWORD(destKey, L"NoRepair", 1);