Various CMake fixes and cleanup

[jamiesnape]

Do not set redundant macOS-related policy; CMP0042 is enabled by virtue of requiring CMake 3.0 on macOS. Do not require a C compiler; there is no C code. Fix typo in CMAKE_INSTALL_FULL_LIBDIR variable name; there is no such variable CMAKE_INSTALL_LIBDIR_FULL. Remove redundant set of CMAKE_SHARED_MODULE_PREFIX; there are no modules being built.

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This change is 

[jamiesnape]

Note apparently master is broken on Mac per https://travis-ci.org/flexible-collision-library/fcl/builds/480449098.

[sherm1]

Thanks, @jamiesnape -- with a few minor comments. Also, would you please edit the PR description to summarize the changes you're making here and why?

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved

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CMakeLists.txt, line 4 at r1 (raw file):

# vi: set ft=cmake :

# Copyright (c) 2012, Willow Garage, Inc.

BTW why add an old Willow Garage copyright? Are you thinking this was inadvertently left off long ago?

Consider also adding
`# Copyright (c) 2019, Toyota Research Institute, Inc.

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CMakeModules/CompilerSettings.cmake, line 4 at r1 (raw file):

# vi: set ft=cmake :

# Copyright (c) 2013, Willow Garage, Inc.

BTW same comment

[jamiesnape]

Reviewable status: complete! all files reviewed, all discussions resolved

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CMakeLists.txt, line 4 at r1 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

BTW why add an old Willow Garage copyright? Are you thinking this was inadvertently left off long ago?

Consider also adding
`# Copyright (c) 2019, Toyota Research Institute, Inc.

Yes, according to git. If you wanted to add a TRI copyright, 2016 looks to be correct date.

[jamiesnape]

(Also I would encourage you to accept un-squashed PR's on occasion; there are numerous small issues with the CMake that are not especially related, and making separate micro-PR's seems inefficient for CI and reviewers' time.)

Reviewable status: complete! all files reviewed, all discussions resolved

[sherm1]

Thanks, Jamie. I'll merge-commit this one so that the individual commits are preserved.

Reviewed 2 of 2 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved