host: use git-version-gen/tarball-v. from topdir

Use .tarball-version from the topdir, because it only gets written there
when generating the OBS package. Remove the duplicate git-version-gen
script and use the one from the topdir to generate a version string if
building from the git tree.

Related: OS#4413
Change-Id: I4b197a218ab44632ff182ffbd72e15c2b20db341

host/Makefile.am

@@ -3,7 +3,7 @@ AUTOMAKE_OPTIONS = foreign dist-bzip2 1.6
 AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
 SUBDIRS = include lib src contrib #tests examples doc
 
-EXTRA_DIST = .version git-version-gen
+EXTRA_DIST = .version
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libosmo-simtrace2.pc