tcg: Fix --disable-tcg build breakage

tcg: Fix --disable-tcg build breakage

Fix the --disable-tcg breakage introduced by 8bca9a03ec60d:

    $ configure --disable-tcg
    [...]
    $ make -C i386-softmmu exec.o
    make: Entering directory 'i386-softmmu'
      CC      exec.o
    In file included from source/qemu/exec.c:62:0:
    source/qemu/include/exec/ram_addr.h:96:6: error: conflicting types for ‘tb_invalidate_phys_range’
     void tb_invalidate_phys_range(ram_addr_t start, ram_addr_t end);
          ^~~~~~~~~~~~~~~~~~~~~~~~
    In file included from source/qemu/exec.c:24:0:
    source/qemu/include/exec/exec-all.h:309:6: note: previous declaration of ‘tb_invalidate_phys_range’ was here
     void tb_invalidate_phys_range(target_ulong start, target_ulong end);
          ^~~~~~~~~~~~~~~~~~~~~~~~
    source/qemu/exec.c:1043:6: error: conflicting types for ‘tb_invalidate_phys_addr’
     void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr, MemTxAttrs attrs)
          ^~~~~~~~~~~~~~~~~~~~~~~
    In file included from source/qemu/exec.c:24:0:
    source/qemu/include/exec/exec-all.h:308:6: note: previous declaration of ‘tb_invalidate_phys_addr’ was here
     void tb_invalidate_phys_addr(target_ulong addr);
          ^~~~~~~~~~~~~~~~~~~~~~~
    make: *** [source/qemu/rules.mak:69: exec.o] Error 1
    make: Leaving directory 'i386-softmmu'

Tested to build x86_64-softmmu and i386-softmmu targets.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180629200710.27626-1-f4bug@amsat.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>