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

 # PPL options

 choice

     bool

     prompt "PPL version"

 # Don't remove next line

 # CT_INSERT_VERSION_BELOW

 config PPL_V_0_11_2

     bool

     prompt "0.11.2"

     select PPL_0_11

 config PPL_V_0_11_1

     bool

     prompt "0.11.1"

     select PPL_0_11

 config PPL_V_0_11

     bool

     prompt "0.11"

     select PPL_0_11

 config PPL_V_0_10_2

     bool

     prompt "0.10.2"

 endchoice

 config PPL_VERSION

     string

 # Don't remove next line

 # CT_INSERT_VERSION_STRING_BELOW

     default "0.11.2" if PPL_V_0_11_2

     default "0.11.1" if PPL_V_0_11_1

     default "0.11" if PPL_V_0_11

     default "0.10.2" if PPL_V_0_10_2

 # For PPL 0.11, we need to pull libpwl if configured static

 config PPL_0_11

     bool

     select PPL_NEEDS_LIBPWL if ! COMPLIBS_SHARED

 config PPL_NEEDS_LIBPWL

     bool