[CMake] Use only keyword-version of target_link_library. NFC.

[CMake] Use only keyword-version of target_link_library. NFC.

CMake insists that for each target, one uses only the non-keyword
version of target_link_library

    target_link_library(mytarget lib)

or the one with PUBLIC/PRIVATE/INTERFACE keyword:

    target_link_library(mytarget PUBLIC lib)

Otherwise, CMake fails with the error message:

  The keyword signature for target_link_libraries has already been used with
  the target "mytarget".  All uses of target_link_libraries with a target
  must be either all-keyword or all-plain.

Change all occurances of target_link_library to the newer keyworded
version to avoid such errors. Some already have been changed in r319840,
but might not be sufficient for all build configurations to build
the doxygen manual.

Reported-by: Tanya Lattner <tanyalattner@llvm.org>
git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@322376 91177308-0d34-0410-b5e6-96231b3b80d8