bugfix: load handlers and use factory symbol

Use a predefined factory symbol to build each handler after loading the
library.

Change-Id: I0369c6e46a57c2e8533409d8b06eb74a3962434c
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/configure.ac b/configure.ac
index efdd0b8..db3bc83 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,7 +17,7 @@
 AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CXXFLAGS])
 
 # Checks for library functions.
-LT_INIT([dlopen]) # Required for systemd linking
+LT_INIT([dlopen disable-static shared]) # Required for systemd linking
 LT_LIB_DLLOAD
 
 # Checks for libraries.