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Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`.  Use `clang-format` version 6.0.

* If you reached this commit for a line in `git blame`, re-run the blame
  operation starting at the parent of this commit to see older history
  for the content.

* See the parent commit for instructions to rebase a change across this
  style transition commit.

Run the `Utilities/Scripts/clang-format.bash` script to update
all our C++ code to a new style defined by `.clang-format`.
Use `clang-format` version 3.8.

* If you reached this commit for a line in `git blame`, re-run the blame
  operation starting at the parent of this commit to see older history
  for the content.

* See the parent commit for instructions to rebase a change across this
  style transition commit.

Sort include directives within each block (separated by a blank line) in
lexicographic order (except to prioritize `sys/types.h` first).  First
run `clang-format` with the config file:

    ---
    SortIncludes: false
    ...

Commit the result temporarily.  Then run `clang-format` again with:

    ---
    SortIncludes: true
    IncludeCategories:
      - Regex:    'sys/types.h'
        Priority: -1
    ...

Commit the result temporarily.  Start a new branch and cherry-pick the
second commit.  Manually resolve conflicts to preserve indentation of
re-ordered includes.  This cleans up the include ordering without
changing any other style.

Use the following command to run `clang-format`:

    $ git ls-files -z -- \
        '*.c' '*.cc' '*.cpp' '*.cxx' '*.h' '*.hh' '*.hpp' '*.hxx' |
      egrep -z -v '(Lexer|Parser|ParserHelper)\.' |
      egrep -z -v '^Source/cm_sha2' |
      egrep -z -v '^Source/(kwsys|CursesDialog/form)/' |
      egrep -z -v '^Utilities/(KW|cm).*/' |
      egrep -z -v '^Tests/Module/GenerateExportHeader' |
      egrep -z -v '^Tests/RunCMake/CommandLine/cmake_depends/test_UTF-16LE.h' |
      xargs -0 clang-format -i

This selects source files that do not come from a third-party.

Inspired-by: Daniel Pfeifer <daniel@pfeifer-mail.de>

Unit tests for the square root of "-25" currently fail when USE_MYMATH
is disabled. The "mysqrt" method in the tutorials, returns "0" for a
negative value, while "sqrt" returns "NaN", and therefore the output is
not accepted by the test.

This patch checks if the number is negative and eventually returns "0"
before calling "sqrt" or "mysqrt" to fix this issue.

Printing a NaN might cause issues with the string catched by the tests
on some platform. Therefore assume that "0" is correct and "fix" the
USE_MYMATH=OFF version by checking if the number is negative and
eventually returning "0" before calling "sqrt" or "mysqrt".