sim: Fix definition of SIM_ARANGE_INLINE

sim: Fix definition of SIM_ARANGE_INLINE

If HAVE_INLINE is false, SIM_ARANGE_INLINE is currently defined as

    #define SIM_ARANGE_INLINE EXTERN

However, EXTERN is not defined anywhere, leading to errors such as:

    In file included from
    /mipt-mips/simulator/../../sim/common/sim-basics.h:147:0,
                     from /mipt-mips/simulator/export/gdb/sim-main.h:13,
                     from /mipt-mips/simulator/export/gdb/gdb_interface.cpp:7:
    /mipt-mips/simulator/../../sim/common/sim-arange.h:71:27: error: ‘EXTERN’
    does not name a type; did you mean ‘EUSERS’?
     #define SIM_ARANGE_INLINE EXTERN
                               ^
    /mipt-mips/simulator/../../sim/common/sim-arange.h:76:1: note: in expansion
    of macro ‘SIM_ARANGE_INLINE’
     SIM_ARANGE_INLINE int
     ^~~~~~~~~~~~~~~~~

I (Simon) have reproduced the problem by simply removing the HAVE_INLINE
definition.  This was originally reported by Pavel I. Kryukov
<kryukov@frtk.ru>.

sim/common/ChangeLog:

	* sim-arange.h (SIM_ARANGE_INLINE): Change EXTERN to extern.