Change how we create the 'ganeti' symlink
Change how we create the 'ganeti' symlink

Currently, if one runs 'make' in an already fully-built tree, this is
the result:

  cd . && test -h "ganeti" || { rm -f ganeti && ln -s lib ganeti; }
  make  all-am
  make[1]: Entering directory `/tmp/test'
  cd . && test -h "ganeti" || { rm -f ganeti && ln -s lib ganeti; }
  make[1]: Leaving directory `/tmp/test'

This is because commit dc7d2c49 added 'ganeti' (which is a PHONY
target) to BUILT_SOURCES, and since that is a dependency of other,
real targets, it means the ganeti target is always remade.

To fix this, we keep ganeti as a PHONY target, but we remove it from
the 'built_base_sources' target, and instead we only remake it
manually in the stamp-directories target. A make run now is just:

  make  all-am
  make[1]: Entering directory `/tmp/test'
  make[1]: Nothing to be done for `all-am'.
  make[1]: Leaving directory `/tmp/test'

Note that we can't get rid of the all-am since we use BUILT_SOURCES.

We also remove the comment of BUILT_SOURCES since it no longer depends
on PHONY targets.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>

andir/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,ganeti/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,dimara/ganeti,mbakke/ganeti,apyrgio/snf-ganeti,bitemyapp/ganeti,apyrgio/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,yiannist/ganeti,ganeti/ganeti,bitemyapp/ganeti,apyrgio/ganeti,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,yiannist/ganeti,leshchevds/ganeti,mbakke/ganeti,dimara/ganeti,onponomarev/ganeti,leshchevds/ganeti,andir/ganeti,mbakke/ganeti