build: Set pkg-config Requires

libopenpower-dbus-interfaces has a dependency on libsystemd.

Change-Id: I8d50896087e873e374d80c1dc2c97fd8d6352f34
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/configure.ac b/configure.ac
index 09cfed9..96bb1dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -26,6 +26,10 @@
     AS_IF([test "x$SDBUSPLUSPLUS" == "x"],
         AC_MSG_ERROR([Cannot find sdbus++]))
 
+    # Checks for libraries.
+    AX_PKG_CHECK_MODULES([SYSTEMD], [], [libsystemd >= 221], [],)
+    AX_PKG_CHECK_MODULES([SDBUSPLUS], [], [sdbusplus], [],)
+
     # Check for baseline language coverage in the compiler for the C++14 standard
     AX_CXX_COMPILE_STDCXX_17([noext])
     AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CFLAGS])
diff --git a/openpower-dbus-interfaces.pc.in b/openpower-dbus-interfaces.pc.in
index 7018987..5ec151e 100644
--- a/openpower-dbus-interfaces.pc.in
+++ b/openpower-dbus-interfaces.pc.in
@@ -7,5 +7,6 @@
 Description: Generated sdbusplus bindings for openpower-dbus-interfaces.
 URL: https://github.com/openbmc/openpower-dbus-interfaces
 Version: @VERSION@
+Requires.private: @AX_PACKAGE_REQUIRES_PRIVATE@
 Libs: -L@libdir@ -lopenpower_dbus
 Cflags: -I@includedir@