sim: endian: move bfd.h from header to source

The bfd APIs are used only by sim-n-endian.h which is only included by
sim-endian.c, so move the bfd.h include there and out of sim-endian.h
which is included by many other modules.

sim/common/sim-endian.c

diff --git a/sim/common/sim-endian.c b/sim/common/sim-endian.c
index 647795b..92c6618 100644
--- a/sim/common/sim-endian.c
+++ b/sim/common/sim-endian.c
@@ -26,6 +26,8 @@
 /* This must come before any other includes.  */
 #include "defs.h"
 
+#include "bfd.h"
+
 #include "sim-basics.h"
 #include "sim-assert.h"
 

sim/common/sim-endian.h

diff --git a/sim/common/sim-endian.h b/sim/common/sim-endian.h
index 9d46db2..b6d97f5 100644
--- a/sim/common/sim-endian.h
+++ b/sim/common/sim-endian.h
@@ -23,8 +23,6 @@
 #ifndef SIM_ENDIAN_H
 #define SIM_ENDIAN_H
 
-#include "bfd.h"
-
 /* C byte conversion functions */
 
 INLINE_SIM_ENDIAN(unsigned_1) endian_h2t_1(unsigned_1 x);