Revert "osmo-config-merge: Add manual page"

This reverts commit 6dd00d876e2b947e070f776f90fbb8305a237d21.

Unfortunately, it seems older a2x versions don't support "-D" for
manpage generation:

All the osmocom master builds started to fail with:

make[2]: Entering directory '/build/deps/libosmocore/man'
a2x --doctype manpage --format manpage -D . osmo-config-merge.adoc
a2x: WARNING: --destination-dir option is only applicable to HTML based outputs
a2x: ERROR: "xmllint" --nonet --noout --valid "/build/deps/libosmocore/man/osmo-config-merge.xml" returned
non-zero exit status 127
Makefile:545: recipe for target 'osmo-config-merge.8' failed

Change-Id: I0f45362d3e978c328d962a5c0d883eade27b875c
diff --git a/Makefile.am b/Makefile.am
index 745d482..de5eb35 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,7 @@
 ACLOCAL_AMFLAGS = -I m4
 
 AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
-SUBDIRS = include src src/vty src/codec src/gsm src/coding src/gb src/ctrl src/sim src/pseudotalloc utils tests man
+SUBDIRS = include src src/vty src/codec src/gsm src/coding src/gb src/ctrl src/sim src/pseudotalloc utils tests
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libosmocore.pc libosmocodec.pc libosmovty.pc libosmogsm.pc \