Find and link libsystemd

libsystemd is a dependency since D89484998,
so find it via pkg-config and link it in.

Author: mszabo-wikia

CMake/Findsystemd.cmake

@@ -0,0 +1,10 @@
+find_package(PkgConfig)
+pkg_check_modules(SYSTEMD libsystemd)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(
+  systemd
+  DEFAULT_MSG
+  SYSTEMD_LIBRARIES
+  SYSTEMD_INCLUDEDIR)
+  

CMake/HPHPFindLibs.cmake

@@ -272,6 +272,7 @@ if (APPLE)
 endif()
 
 if (LINUX)
+  find_package(systemd REQUIRED)
   find_package(Bpf REQUIRED)
 endif()
 
@@ -337,7 +338,7 @@ macro(hphp_link target)
   target_link_libraries(${target} ${VISIBILITY} glog)
 
   if (LINUX)
-    target_link_libraries(${target} ${VISIBILITY} ${BPF_LIBRARIES})
+    target_link_libraries(${target} ${VISIBILITY} ${BPF_LIBRARIES} ${SYSTEMD_LIBRARIES})
   endif()
 
   if (LIBINOTIFY_LIBRARY)

ci/ubuntu-20.04-focal/debian/control

@@ -53,6 +53,7 @@ Build-Depends:
   libsodium-dev,
   libsqlite3-dev,
   libssl-dev,
+  libsystemd-dev,
   libtool,
   libxml2-dev,
   libxslt1-dev,