oss-fuzz/build.sh: use heredoc for script creation

Rather than a quoted multi-line echo.

Change-Id: Ib51fa5693f2946e2bc991dc66a6b3449e6ee61c0

tests/fuzzer/oss-fuzz/build.sh

@@ -70,13 +70,15 @@ for fuzz_main_file in $FUZZ_TEST_BINARIES_OUT_PATHS; do
   for fuzz_entrypoint in $FUZZ_TESTS; do
     TARGET_FUZZER="${fuzz_basename}@$fuzz_entrypoint"
     # Write executer script
-    echo "#!/bin/sh
+    cat << EOF > $OUT/$TARGET_FUZZER
+#!/bin/sh
 # LLVMFuzzerTestOneInput for fuzzer detection.
 this_dir=\$(dirname \"\$0\")
 export TEST_DATA_DIRS=\$this_dir/corpus
 chmod +x \$this_dir/$fuzz_basename
 \$this_dir/$fuzz_basename --fuzz=$fuzz_entrypoint -- \$@
-chmod -x \$this_dir/$fuzz_basename" > $OUT/$TARGET_FUZZER
+chmod -x \$this_dir/$fuzz_basename
+EOF
     chmod +x $OUT/$TARGET_FUZZER
   done
   # Copy data.