COMP: Update ITKv4 to fix Gcc 4.2.1 Apple compiler seg fault

Following r22163, ITKv4 hash tag has been updated to point to the release
branch. This introduced the regression documented in [1]

This commit fixes the problem by including the ITK commit f49a7db7. For
sake of completeness, the corresponding message is also reported below.

[1] https://itk.icts.uiowa.edu/jira/browse/ITK-3172


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BUG: Disable aligned attribute to fix Apple GCC 4.2.1 seg
 fault

Commit 2f96c578 fixed the configure test checking if aligned
attributes were supported by the compiler. Then commit e906441e
disabled the test for Gcc 4.1 to prevent a similar error.

This commit ensures that the configure test also excludes Apple
Gcc 4.2.1 (without llvm support) by forcing the configure test to
be in "Debug" mode.

When this issue was first encountered by Brad, the problem was occurring
in Debug mode and he narrowed it down to the block of code in the try_compile
and tried to use it as a detector. Slicer appears to have encountered the
same issue in release mode, but the bug detector only detects it in Debug
mode.

Co-authored-by: Bradley Lowekamp <blowekamp@mail.nih.gov>
// --------------------

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22171 3bd1e089-480b-0410-8dfb-8563597acbee