scripts: refine static linking check to better guide the user

The current mechanism to check if static linking is possible, and the mesage
displayed on failure, can be puzzling to the unsuspecting user.

Also, the current implementation is not using the existing infrastructure,
and is thus difficult to enhance with new tests.

So, switch to using the standard CT_DoExecLog infra, and use four tests to
check for the host compiler:
- check we can run it
- check it can build a trivial program
- check it can statically link that program
- check if it statically link with libstdc++

That should cover most of the problems. Hopefully.

(At the same time, fix a typo in a comment)

Signed-off-by: Daniel Price <daniel.price@gmail.com>
[yann.morin.1998@free.fr: split original patch for self-contained changes]
[yann.morin.1998@free.fr: use steps to better see gcc's output]
[yann.morin.1998@free.fr: commit log]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <163f86b5216fc08c672a.1353459722@nipigon.dssd.com>
Patchwork-Id: 200536

 # Wrapper to build the companion libs facilities

 # List all companion tools facilities, and parse their scripts

 CT_COMP_LIBS_FACILITY_LIST=

 for f in "${CT_LIB_DIR}/scripts/build/companion_libs/"*.sh; do

     _f="$(basename "${f}" .sh)"

     _f="${_f#???-}"

     . "${f}"

     CT_COMP_LIBS_FACILITY_LIST="${CT_COMP_LIBS_FACILITY_LIST} ${_f}"

 done

 # Download the companion libs facilities

 do_companion_libs_get() {

     for f in ${CT_COMP_LIBS_FACILITY_LIST}; do

         do_${f}_get

     done

 }

 # Extract and patch the companion libs facilities

 do_companion_libs_extract() {

     for f in ${CT_COMP_LIBS_FACILITY_LIST}; do

         do_${f}_extract

     done

 }

 # Build the companion libs facilities for build

 do_companion_libs_for_build() {

     for f in ${CT_COMP_LIBS_FACILITY_LIST}; do

         do_${f}_for_build

     done

 }

 # Build the companion libs facilities for host

 do_companion_libs_for_host() {

     for f in ${CT_COMP_LIBS_FACILITY_LIST}; do

         do_${f}_for_host

     done

 }