sim: cgen: inline cgen_init logic

This function has done only one thing: post-process command line
settings to see if profiling or tracing has been enabled, and if
so, set the run_fast_p flag in the simulator state.  That flag is
only used in one place: to select the fast or slow cgen engine.
By inlining the run_fast_p logic to the one place it's used, we
can delete a good amount of logic specific to cgen ports: both
the call to cgen_init and the conditional simulator state.  This
in turn allows us to have a single simulator state struct across
all ports so we can share objects more between them, and makes
the sim_open calls look more consistent.

sim/common/cgen-defs.h

@@ -138,22 +138,8 @@ typedef enum {
 #define ENDSWITCH(N)
 #endif
 
-/* Simulator state.  */
-
-/* CGEN_STATE contains additional state information not present in
-   sim_state_base.  */
-
-typedef struct cgen_state {
-  /* Non-zero if no tracing or profiling is selected.  */
-  int run_fast_p;
-#define STATE_RUN_FAST_P(sd) (STATE_CGEN_STATE (sd).run_fast_p)
-} CGEN_STATE;
-
 /* Various utilities.  */
 
-/* Called after sim_post_argv_init to do any cgen initialization.  */
-extern void cgen_init (SIM_DESC);
-
 /* Return the name of an insn.  */
 extern CPU_INSN_NAME_FN cgen_insn_name;