install man pages according to ngspice package

Patch provided by Fabio Rossi

man/man1/Makefile.am

@@ -1,9 +1,21 @@
 ## Process this file with automake to produce Makefile.in
 
 
-man_MANS = ngspice.1 ngnutmeg.1 ngsconvert.1 ngmultidec.1 cmpp.1 ngmakeidx.1 ngproc2mod.1
+man_MANS =
 
+if XSPICE_WANTED
+man_MANS += cmpp.1
+endif XSPICE_WANTED
 
-EXTRA_DIST = $(man_MANS)
+if !TCL_MODULE
+if !SHARED_MODULE
+man_MANS += ngspice.1
+if OLDAPPS
+man_MANS += ngnutmeg.1 ngsconvert.1 ngmultidec.1 ngmakeidx.1 ngproc2mod.1
+endif OLDAPPS
+endif !SHARED_MODULE
+endif !TCL_MODULE
+
+EXTRA_DIST = ngspice.1 ngnutmeg.1 ngsconvert.1 ngmultidec.1 cmpp.1 ngmakeidx.1 ngproc2mod.1
 
 MAINTAINERCLEANFILES = Makefile.in