[#3393] ignore error in libyang tests

... and add bison and flex to ubuntu for completion

Author: andrei-pavel

Diff for: hammer.py

@@ -1133,7 +1133,7 @@ def _install_libyang_from_sources(ignore_errors = False):
         execute('git clone https://github.com/CESNET/libyang.git ~/.hammer-tmp/libyang')
         execute(f'git checkout {version}', cwd='~/.hammer-tmp/libyang')
         execute('mkdir ~/.hammer-tmp/libyang/build')
-        execute('cmake  ..', cwd='~/.hammer-tmp/libyang/build')
+        execute('cmake -DBUILD_TESTING=OFF -DCMAKE_C_FLAGS="-Wno-incompatible-pointer-types" ..', cwd='~/.hammer-tmp/libyang/build')
         execute('make -j $(nproc || gnproc || echo 1)', cwd='~/.hammer-tmp/libyang/build')
         execute('sudo make install', cwd='~/.hammer-tmp/libyang/build')
         system, revision = get_system_revision()
@@ -1169,7 +1169,7 @@ def _install_sysrepo_from_sources(ignore_errors = False):
         execute('git clone https://github.com/sysrepo/sysrepo.git ~/.hammer-tmp/sysrepo')
         execute(f'git checkout {version}', cwd='~/.hammer-tmp/sysrepo')
         execute('mkdir ~/.hammer-tmp/sysrepo/build')
-        execute('cmake -DREPO_PATH=/etc/sysrepo ..', cwd='~/.hammer-tmp/sysrepo/build')
+        execute('cmake -DBUILD_TESTING=OFF -DREPO_PATH=/etc/sysrepo ..', cwd='~/.hammer-tmp/sysrepo/build')
         execute('make -j $(nproc || gnproc || echo 1)', cwd='~/.hammer-tmp/sysrepo/build')
         execute('sudo make install', cwd='~/.hammer-tmp/sysrepo/build')
         system, revision = get_system_revision()
@@ -1847,7 +1847,7 @@ def link_pg_config():
         _apt_update(system, revision, env=env, check_times=check_times, attempts=3, sleep_time_after_attempt=10)
 
         packages = ['gcc', 'g++', 'make', 'autoconf', 'automake', 'libtool', 'libssl-dev', 'liblog4cplus-dev',
-                    'libboost-system-dev', 'gnupg', 'libpcap-dev']
+                    'libboost-system-dev', 'gnupg', 'libpcap-dev', 'bison', 'flex']
 
         if 'docs' in features:
             packages.extend(['python3-sphinx', 'python3-sphinx-rtd-theme',