qemu/osdep: Remove fallback for MAP_FIXED_NOREPLACE

In order for our emulation of MAP_FIXED_NOREPLACE to succeed within
linux-user target_mmap, we require a non-zero value.  This does not
require host kernel support, merely the bit being defined.

MAP_FIXED_NOREPLACE was added with glibc 2.28.  From repology.org:

                  Fedora 36: 2.35
          CentOS 8 (RHEL-8): 2.28
                  Debian 11: 2.31
         OpenSUSE Leap 15.4: 2.31
           Ubuntu LTS 20.04: 2.31

Reported-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230808164418.69989-1-richard.henderson@linaro.org>

include/qemu/osdep.h

@@ -289,9 +289,6 @@ void QEMU_ERROR("code path is reachable")
 #ifndef MAP_ANONYMOUS
 #define MAP_ANONYMOUS MAP_ANON
 #endif
-#ifndef MAP_FIXED_NOREPLACE
-#define MAP_FIXED_NOREPLACE 0
-#endif
 #ifndef MAP_NORESERVE
 #define MAP_NORESERVE 0
 #endif