liquid_fb: Fix decoration config option

The decoration configuration is used by Qt5 to omit window decorations
from menus. It got lost during the restructuring of the scout widgets.
News item for FOSDEM slides
liquid_fb: Fix decoration config option

The decoration configuration is used by Qt5 to omit window decorations
from menus. It got lost during the restructuring of the scout widgets.

Issue #1054
Qt5: reserve screen space for the liquid_fb title bar

With this patch, the liquid_fb title bar height gets reserved at the top of the
screen, so if a Qt application wants to position a window at (0,0), there's
still enough space to show the title bar above.

Issue #1054.
tool_chain: check for various autoconf installs.

There exist different default setups for a specific autoconf version:
* autoconf
* autoconf$(VERSION)
* autoconf-$(VERSION)

As of now, only the second option is recognized by the check in tool_chain.

This patch ensures that if one of those is present in the correct
version, it will be found and used in the build process.

Fixes #1053.
base: optional length argument for String::String
Add 'operator *' to os/volatile_object.h

This operator is needed when we want to create a reference to (the
content of) a volatile object.
Accessors for Xml_node utility

This patch adds accessors to obtain the buffer of an attribute value,
which is useful to avoid the copying-out of such information by
maintaining pointers into the XML string as meta data.
fixup "base: Add 'construct_at' utility"
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