Add CMakeLists.txt files to dist tarball generated by autotools

This is half of the work to align the cmake and autotools generated dist tarballs.
What's missing in the cmake dist tarball on my system are all the files generated
or installed by running autogen.sh. I can't test this because cmake can't run
my version of automake (1.15), or at least our CMake configuration prevents this from happening.

lib/Makefile.am

@@ -4,5 +4,5 @@ else
 SUBDIRS = libc
 endif
 
-EXTRA_DIST = README
+EXTRA_DIST = README CMakeLists.txt
 

lib/libc/Makefile.am

@@ -17,7 +17,8 @@ EXTRA_libc_missing_la_SOURCES = \
   localtime_r.c \
   setenv.c \
   strfmon.c \
-  strptime.c
+  strptime.c \
+  CMakeLists.txt
 
 # This will automatically be filled in with the necessary object file
 # names.  Configure does this based upon the AC_REPLACE_FUNCS macros.

lib/stf/Makefile.am

@@ -10,4 +10,4 @@ libgnc_stf_la_LIBADD = $(GOFFICE_LIBS)
 
 AM_CPPFLAGS = $(GOFFICE_CFLAGS)
 
-EXTRA_DIST = $(REALSRCS) $(REALHDRS)
+EXTRA_DIST = $(REALSRCS) $(REALHDRS) CMakeLists.txt