Move build script from oss-fuzz repo to here.

This requires a change in the oss-fuzz repo similar to
https://github.com/AOMediaCodec/libavif/blob/main/tests/oss-fuzz/build.sh

Change-Id: I7bcdb52dcec7e6edd926aea93988cd758ef9a854

tests/fuzzer/oss-fuzz/build.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+# Copyright 2018 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+set -eu
+
+# limit allocation size to reduce spurious OOMs
+WEBP_CFLAGS="$CFLAGS -DWEBP_MAX_IMAGE_SIZE=838860800" # 800MiB
+
+./autogen.sh
+CFLAGS="$WEBP_CFLAGS" ./configure \
+  --enable-asserts \
+  --enable-libwebpdemux \
+  --enable-libwebpmux \
+  --disable-shared \
+  --disable-jpeg \
+  --disable-tiff \
+  --disable-gif \
+  --disable-wic
+make clean
+make -j$(nproc)
+
+find $SRC/libwebp-test-data -type f -size -32k -iname "*.webp" \
+  -exec zip -qju fuzz_seed_corpus.zip "{}" \;
+
+webp_libs=(
+  src/demux/.libs/libwebpdemux.a
+  src/mux/.libs/libwebpmux.a
+  src/.libs/libwebp.a
+  imageio/.libs/libimageio_util.a
+  sharpyuv/.libs/libsharpyuv.a
+)
+webp_c_fuzzers=(
+  advanced_api_fuzzer
+  animation_api_fuzzer
+  huffman_fuzzer
+  mux_demux_api_fuzzer
+  simple_api_fuzzer
+)
+webp_cxx_fuzzers=(
+  animdecoder_fuzzer
+  animencoder_fuzzer
+  enc_dec_fuzzer
+)
+
+for fuzzer in "${webp_c_fuzzers[@]}"; do
+  $CC $CFLAGS -Isrc -I. tests/fuzzer/${fuzzer}.c -c -o tests/fuzzer/${fuzzer}.o
+  $CXX $CXXFLAGS $LIB_FUZZING_ENGINE \
+    tests/fuzzer/${fuzzer}.o -o $OUT/${fuzzer} \
+    "${webp_libs[@]}"
+done
+
+for fuzzer in "${webp_cxx_fuzzers[@]}"; do
+  $CXX $CXXFLAGS -Isrc -I. $LIB_FUZZING_ENGINE \
+    tests/fuzzer/${fuzzer}.cc -o $OUT/${fuzzer} \
+    "${webp_libs[@]}"
+done
+
+for fuzzer in "${webp_c_fuzzers[@]}" "${webp_cxx_fuzzers[@]}"; do
+  cp fuzz_seed_corpus.zip $OUT/${fuzzer}_seed_corpus.zip
+  cp tests/fuzzer/fuzz.dict $OUT/${fuzzer}.dict
+done