build: Fixed Visual Studio project file generator missing some files

As of commit 6cdd88f22c the Visual Studio project file generator would
skip the first and last file from each group of files.

projects/generate.bat

@@ -126,6 +126,8 @@ rem
     set "TABS=      "
   )
 
+  call :extension %3 ext
+
   if "%1" == "dsp" (
     echo # Begin Source File>> %4
     echo.>> %4
@@ -141,8 +143,6 @@ rem
     echo %TABS%^>>> %4
     echo %TABS%^</File^>>> %4
   ) else if "%1" == "vcxproj" (
-    call :extension %3 ext
-
     if "%ext%" == "c" (
       echo %SPACES%^<ClCompile Include=^"..\..\..\..\%2\%~3^" /^>>> %4
     ) else if "%ext%" == "h" (