Fix bsd-user build errors after 8642c1b

  LINK  sparc-bsd-user/qemu-sparc
bsd-user/main.o: In function `cpu_loop':
/home/sbruno/bsd/qemu/bsd-user/main.c:515: undefined reference to `cpu_sparc_exec'
c++: error: linker command failed with exit code 1 (use -v to see invocation)
gmake[1]: *** [Makefile:197: qemu-sparc] Error 1
gmake: *** [Makefile:204: subdir-sparc-bsd-user] Error 2

  LINK  i386-bsd-user/qemu-i386
bsd-user/main.o: In function `cpu_loop':
/home/sbruno/bsd/qemu/bsd-user/main.c:174: undefined reference to `cpu_x86_exec'
c++: error: linker command failed with exit code 1 (use -v to see invocation)
gmake[1]: *** [Makefile:197: qemu-i386] Error 1
gmake: *** [Makefile:204: subdir-i386-bsd-user] Error 2

Signed-off-by:  Sean Bruno <sbruno@freebsd.org>
Message-id: 20160729160235.64525-1-sbruno@freebsd.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

bsd-user/main.c

@@ -171,7 +171,7 @@ void cpu_loop(CPUX86State *env)
     //target_siginfo_t info;
 
     for(;;) {
-        trapnr = cpu_x86_exec(cs);
+        trapnr = cpu_exec(cs);
         switch(trapnr) {
         case 0x80:
             /* syscall from int $0x80 */
@@ -512,7 +512,7 @@ void cpu_loop(CPUSPARCState *env)
     //target_siginfo_t info;
 
     while (1) {
-        trapnr = cpu_sparc_exec(cs);
+        trapnr = cpu_exec(cs);
 
         switch (trapnr) {
 #ifndef TARGET_SPARC64