build: pkg anti-pattern: use defaults

Use the defaults in the pkg check where the default error message is
sufficient to identify which package is missing.

Change-Id: I16bdbf34b753bdf91dfa4dac824ffd626fd190f7
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/configure.ac b/configure.ac
index 1ff3c65..be4f46a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,11 +17,11 @@
     [AC_MSG_ERROR([Could not find python-2.7 installed...python-2.7 is required])])
 
 # Checks for libraries.
-PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus],, AC_MSG_ERROR(["Requires sdbusplus package."]))
-PKG_CHECK_MODULES([SDEVENTPLUS], [sdeventplus],, AC_MSG_ERROR(["Requires sdeventplus package."]))
-PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces],, AC_MSG_ERROR(["Requires phosphor-dbus-interfaces package."]))
-PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging],, AC_MSG_ERROR(["Requires phosphor-logging."]))
-PKG_CHECK_MODULES([PHOSPHOR_SNMP], [phosphor-snmp],, AC_MSG_ERROR(["Requires phosphor-snmp."]))
+PKG_CHECK_MODULES([SDBUSPLUS], [sdbusplus])
+PKG_CHECK_MODULES([SDEVENTPLUS], [sdeventplus])
+PKG_CHECK_MODULES([PHOSPHOR_DBUS_INTERFACES], [phosphor-dbus-interfaces])
+PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging])
+PKG_CHECK_MODULES([PHOSPHOR_SNMP], [phosphor-snmp])
 
 # Check for sdbus++
 AC_PATH_PROG([SDBUSPLUSPLUS], [sdbus++])