Include guards on our headers

src/include/86box/smram.h

@@ -14,10 +14,10 @@
  *
  *		Copyright 2016-2020 Miran Grca.
  */
+
 #ifndef EMU_SMRAM_H
 # define EMU_SMRAM_H
 
-
 typedef struct _smram_
 {
     struct _smram_	*prev, *next;
@@ -62,5 +62,4 @@ extern void	smram_state_change(smram_t *smr, int smm, int flags);
 /* Enables or disables the use of a separate SMRAM for addresses below A0000. */
 extern void	smram_set_separate_smram(uint8_t set);
 
-
 #endif	/*EMU_SMRAM_H*/