zsnes call C initialization code from assembler.

Example backtrace:

    Thread 1 "zsnes" received signal SIGSEGV, Segmentation fault.
    => 0xf7550275 <+37>:    vmovdqa (%esp),%xmm1
    ...
    #13 0x5699ef82 in InitSound () at linux/audio.c:336
    #14 0x569a25af in initwinvideo () at linux/sdllink.c:1080
    #15 0x5699fc13 in initvideo () at linux/sdllink.c:1298
    #16 0x56f9d5bc in regptwa ()
    #17 0x56a34b50 in SA1tableG ()
    #18 0x56f84788 in selcB800 ()
    ...

Call to 'initwinvideo' (first C function) looks like that:
  NEWSYM InitPreGame   ; Executes before starting/continuing a game
      mov byte[pressed+1],2
      pushad
      call Start60HZ
  %ifdef __OPENGL__
      call drawscreenwin
  %endif
      call initwinvideo

Note: pushad / call does not 16-byte maintain stack alignment
and breaks i386 ABI.

We apply realignment attribute to all functions noticed by users.
Bug: https://bugs.gentoo.org/503138
--- src/linux/sdllink.c.old
+++ src/linux/sdllink.c
@@ -773,11 +773,11 @@ BOOL InitInput()
 {
   InitJoystickInput();
   return TRUE;
 }
 
-int startgame()
+int __attribute__((force_align_arg_pointer)) startgame()
 {
   static bool ranonce = false;
   int status;
 
   if (!ranonce)
--- a/linux/sdllink.c
+++ b/linux/sdllink.c
@@ -897,7 +897,7 @@ bool OGLModeCheck()
    return(cvidmode > 4);
 }
 
-void initwinvideo(void)
+void __attribute__((force_align_arg_pointer)) initwinvideo(void)
 {
   DWORD newmode = 0;