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

 # MicroBlaze specific config options

 ## depends on EXPERIMENTAL

 ##

 ## select ARCH_SUPPORT_ARCH

 ## select ARCH_FLOAT_SW

 ## select ARCH_SUPPORTS_BOTH_ENDIAN

 ## select ARCH_DEFAULT_BE

 ## select ARCH_SUPPORTS_BOTH_MMU

 ## select ARCH_DEFAULT_HAS_MMU

 ##

 ## help The MicroBlaze architecture, as defined by:

 ## help 	http://www.xilinx.com/

 ## help 

 ## help Upstream projects do not currently provide

 ## help full support for the microblaze architecture

 ## help and as such, this is marked as EXPERIMENTAL

 ## help for CT-NG.

 ## help 

 ## help Support is being added for a modern gcc,

 ## help binutils and gdb along with nptl threading

 ## help in eglibc for microblaze.