installer: loudly warn when installing a 32-bit Git for Windows

The warning is intended to let users know that Git for Windows (i686
variant) is soon no longer going to be serviced.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

installer/install.iss

@@ -1091,6 +1091,10 @@ begin
     UpdateInfFilenames;
 #if BITNESS=='32'
     Result:=True;
+    if not IsWin64 then
+        SuppressibleMsgBox('Git for Windows (32-bit) is nearing its end of support.'+#13+'More information at https://gitforwindows.org/32-bit.html',mbError,MB_OK or MB_DEFBUTTON1,IDOK)
+    else if SuppressibleMsgBox('Git for Windows (32-bit) is nearing its end of support. It is recommended to install the 64-bit variant of Git for Windows instead.'+#13+'More information at https://gitforwindows.org/32-bit.html'+#13+'Continue to install the 32-bit variant?',mbError,MB_YESNO or MB_DEFBUTTON2,IDNO)=IDNO then
+        Result:=False;
 #else
     if not IsWin64 then begin
         LogError('The 64-bit version of Git requires a 64-bit Windows. Aborting.');