scripts/oss-fuzz: add a suppression for keymap

When updating to the latest fedora the santizer found more leaks
inside xkbmap:

  FAILED: pc-bios/keymaps/ar
  /builds/stsquad/qemu/build-oss-fuzz/qemu-keymap -f pc-bios/keymaps/ar -l ara
  =================================================================
  ==3604==ERROR: LeakSanitizer: detected memory leaks
  Direct leak of 1424 byte(s) in 1 object(s) allocated from:
      #0 0x56316418ebec in __interceptor_calloc (/builds/stsquad/qemu/build-oss-fuzz/qemu-keymap+0x127bec) (BuildId: a2ad9da3190962acaa010fa8f44a9269f9081e1c)
      #1 0x7f60d4dc067e  (/lib64/libxkbcommon.so.0+0x1c67e) (BuildId: b243a34e4e58e6a30b93771c256268b114d34b80)
      #2 0x7f60d4dc2137 in xkb_keymap_new_from_names (/lib64/libxkbcommon.so.0+0x1e137) (BuildId: b243a34e4e58e6a30b93771c256268b114d34b80)
      #3 0x5631641ca50f in main /builds/stsquad/qemu/build-oss-fuzz/../qemu-keymap.c:215:11

and many more. As we can't do anything about the library add a
suppression to keep the CI going with what its meant to be doing.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-8-alex.bennee@linaro.org>

scripts/oss-fuzz/lsan_suppressions.txt

@@ -1,2 +1,5 @@
 # The tcmalloc on Fedora37 confuses things
 leak:/lib64/libtcmalloc_minimal.so.4
+
+# libxkbcommon also leaks in qemu-keymap
+leak:/lib64/libxkbcommon.so.0