feat: use meson to build dnsdist fuzz targets

This should fix the Fuzz errors in PowerDNS/pdns#17010

Author: pieterlexis

projects/powerdns/Dockerfile

@@ -18,7 +18,7 @@
 FROM gcr.io/oss-fuzz-base/base-builder
 
 # install required packages to build your project
-RUN apt-get update && apt-get install -y autoconf automake bison dh-autoreconf flex libluajit-5.1-dev libedit-dev libprotobuf-dev libssl-dev libtool make pkg-config protobuf-compiler ragel
+RUN apt-get update && apt-get install -y autoconf automake bison dh-autoreconf flex libluajit-5.1-dev libedit-dev libprotobuf-dev libssl-dev libtool make pkg-config protobuf-compiler ragel meson ninja-build
 RUN wget https://archives.boost.io/release/1.84.0/source/boost_1_84_0.tar.bz2  # Temporarily use manual installation over the outdated libboost-dev package
 
 # checkout all sources needed to build your project

projects/powerdns/build.sh

@@ -58,19 +58,29 @@ cp fuzz_target_* "${OUT}/"
 # build the dnsdist fuzzing target, if any
 if [ -f dnsdistdist/fuzz_dnsdistcache.cc ]; then
     cd dnsdistdist
-    sed -i 's/AC_CC_PIE//' configure.ac
-    autoreconf -vi
-    ./configure \
-        --enable-fuzz-targets \
-        --disable-dependency-tracking \
-        --disable-silent-rules || /bin/bash
-    if [ -d ext/arc4random/ ]; then
-        make -j$(nproc) -C ext/arc4random/
+    build_dir='.'
+    if [ -f configure.ac ]; then
+        sed -i 's/AC_CC_PIE//' configure.ac
+        autoreconf -vi
+        ./configure \
+            --enable-fuzz-targets \
+            --disable-dependency-tracking \
+            --disable-silent-rules || /bin/bash
+        if [ -d ext/arc4random/ ]; then
+            make -j$(nproc) -C ext/arc4random/
+        fi
+        make -j$(nproc) fuzz_targets
+    else
+        build_dir='build'
+        sed -i "/'b_pie=true',/d" meson.build
+        meson setup \
+          -D fuzz-targets=true \
+          ${build_dir}
+        meson compile -C ${build_dir} fuzz-targets
     fi
-    make -j$(nproc) fuzz_targets
 
     # copy the fuzzing target binaries
-    cp fuzz_target_* "${OUT}/"
+    cp ${build_dir}/fuzz_target_* "${OUT}/"
 
     # back to the pdns/ directory
     cd ..