linux-user: Pass missing MAP_ANONYMOUS to target_mmap() call

A target_mmap() call in load_elf_binary() was missing the MAP_ANONYMOUS
flag. (Spotted by Coverity, because target_mmap() will try to use
-1 as the filedescriptor in this case.)

This has never been noticed because the code in question is for
handling ancient SVr4 iBCS2 binaries.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NRiku Voipio <riku.voipio@linaro.org>

linux-user/elfload.c

@@ -2233,7 +2233,7 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info)
                we do not have the power to recompile these, we emulate
                the SVr4 behavior.  Sigh.  */
             target_mmap(0, qemu_host_page_size, PROT_READ | PROT_EXEC,
-                        MAP_FIXED | MAP_PRIVATE, -1, 0);
+                        MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
         }
     }