Fix ram-fs chunk test

The script was missing RM service and had color codes in output to
compare.
Fix compiler warnings
Make Deallocator::need_size_for_free() pure virtual
Revise delete with allocators

Delete operators with additional allocator reference/pointer parameters
are needed if the constructor of an 'new(allocator)' allocated object
throws an exception. Also, destroy now uses the operator to free memory
and provides variants with allocator reference and pointer.

The commit includes a simple test scripts 'run/new_delete', which
exercises the several 'delete' cases.

Related to #1030.
pci_session: add free_dma_buffer call (Fix #1037)
block: free packet stream dataspace on destruction

Fixes #1033
Noux: POSIX signal improvements

- 'kill()' syscall added
- 'wait()' gets unblocked when a signal occurs
- syscalls can get called from a signal handler without corrupting the 'sysio' object
- the child's exit status gets correctly reported to 'wait()'
- SIGCHLD gets ignored by default
- pending signals survive 'execve()'

Fixes #1035.
part_blk.run: build components before block image

With this patch, the components get built before the creation of the block
image to ensure that the 'bin' directory exists.

Fixes #1038.
base: test for races in thread-context allocation

Related to #1024.
doc: Genode Porting Guide + news item