maybe oss-fuzz shares /work and /out

currently the build runs out of space

Change-Id: I24a68051b7fd1df7c55849f27aa43cedc9909b1a
Reviewed-on: https://gerrit.libreoffice.org/36682Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

bin/oss-fuzz-build.sh

@@ -20,6 +20,8 @@ export ASAN_OPTIONS="detect_leaks=0"
 
 make fuzzers
 
+rm -rf workdir
+
 #some minimal fonts required
 cp $SRC/libreoffice/extras/source/truetype/symbol/opens___.ttf instdir/share/fonts/truetype/Liberation* $OUT
 #minimal runtime requirements