Automake wants AM_PROG_CC_C_O in configure.in if a Makefile.am uses two
targets with the same base source file.

--- a/configure.in	2009-01-01 16:36:02.000000000 -0600
+++ b/configure.in	2009-01-01 16:35:51.000000000 -0600
@@ -11,6 +11,8 @@
 dnl Checks for programs.
 AC_PROG_CC
 
+AM_PROG_CC_C_O
+
 dnl Checks for libraries.
 dnl Replace `main' with a function in -lz:
 AC_CHECK_LIB(z, main,, echo "you must install zlib on your system to compile mergelog" ; exit)