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 tools facilities

# List all companion tools facilities, and parse their scripts

CT_COMP_TOOLS_FACILITY_LIST=

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

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

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

    __f="CT_COMP_TOOLS_${_f}"

    if [ "${!__f}" = "y" ]; then

        CT_DoLog DEBUG "Enabling companion tools '${_f}'"

        . "${f}"

        CT_COMP_TOOLS_FACILITY_LIST="${CT_COMP_TOOLS_FACILITY_LIST} ${_f}"

    else

        CT_DoLog DEBUG "Disabling companion tools '${_f}'"

    fi

done

# Download the companion tools facilities

do_companion_tools_get() {

    for f in ${CT_COMP_TOOLS_FACILITY_LIST}; do

        do_companion_tools_${f}_get

    done

}

# Extract and patch the companion tools facilities

do_companion_tools_extract() {

    for f in ${CT_COMP_TOOLS_FACILITY_LIST}; do

        do_companion_tools_${f}_extract

    done

}

# Build the companion tools facilities

do_companion_tools() {

    for f in ${CT_COMP_TOOLS_FACILITY_LIST}; do

        do_companion_tools_${f}_build

    done

}