fixup "base: Add 'construct_at' utility"

ref #989
base: rename reload_parent_cap.cc

ref #989
noux: Noux_connection::context_area_rm_session()

This enables a forked process to update the capability of its
context area RM session.

ref #989
libc_noux & 64bit: fix printf format-warning

Normally for intptr_t the printf format PRIiPTR should be used. As Genode
printf doens't support this format we cast it to long int (intptr_t is int
for 32 bit and long int for 64 bit).

ref #989
noux & 64bit: fix printf format-warning

ref #989
base: setup thread object for main thread in CRT0

For a main thread a thread object is created by the CRT0 before _main gets
called so that _main can already run in a generic environment that, e.g.,
catches stack overflows as a page-fault instead of corrupting the BSS.
Additionally dynamic programs have only one CRT0 - the one of the LDSO -
which does the initialization for both LDSO and program.

ref #989
base: ease Platform_env::Resources

It is unnecessary to remember session caps in a Resources object as the
contained connections can cast implicitely to the appropriate caps.

ref #989
noux_fork: raise MAX_COUNT to 1000

To see the output of both, forker and fork, we must give the test
more time on OKL4 as fork seems to be not so fast with this kernel.

ref #989
base: generic implementation of Context_allocator

ref #989
base: bin out-commented EH_FRAME stuff in CRT0s

ref #989
base: downsize initial main-thread stack

As the initial main-thread stack is not used for the whole main-thread life
anymore but only for the initialization of the Genode environment it can be
downsized to 32Kb for all architectures.

ref #989
base: beautify BSS stuff in CRT0s

fix #989