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

diff -durN gcc-4.4.4.orig/gcc/stmt.c gcc-4.4.4/gcc/stmt.c

--- gcc-4.4.4.orig/gcc/stmt.c	2010-03-08 12:46:28.000000000 +0100

+++ gcc-4.4.4/gcc/stmt.c	2010-05-16 19:12:31.000000000 +0200

@@ -2377,7 +2377,11 @@

 	  use_cost_table

 	    = (TREE_CODE (orig_type) != ENUMERAL_TYPE

 	       && estimate_case_costs (case_list));

-	  balance_case_nodes (&case_list, NULL);

+	  /* When optimizing for size, we want a straight list to avoid

+	     jumps as much as possible. This basically creates an if-else

+	     chain.  */

+	  if (!optimize_size)

+	    balance_case_nodes (&case_list, NULL);

 	  emit_case_nodes (index, case_list, default_label, index_type);

 	  if (default_label)

 	    emit_jump (default_label);

@@ -2943,6 +2947,7 @@

 	    {

 	      if (!node_has_low_bound (node, index_type))

 		{

+		  if (!optimize_size) /* don't jl to the .default_label. */

 		  emit_cmp_and_jump_insns (index,

 					   convert_modes

 					   (mode, imode,