[liblas]Fix ${_IMPORT_PREFIX} in liblas-depends-*.cmake.

[JackBoosY]

Since liblas generates depends.cmake instead of target.cmake, fix ${_IMPORT_PREFIX} in these cmake files.

Related: #7749.

[JackBoosY]

@pwm1234 Can you test this?

Thanks.

[Neumann-A]

@JackBoosY: This is a case for vcpkg_fixup_cmake_targets

• either improve vcpkg_fixup_cmake_targets to incoparate the case of this port
• or give vcpkg_fixup_cmake_targets an additional parameter like: TARGET_FILENAME which specifies the targetfile which needs to be fixed

[pwm1234]

Yes, I tested your change and the absolute path in the liblas-depends-release.cmake is gone!
Thank you!

[pwm1234]

By the way, if I try to build the release configuration only by putting set(VCPKG_BUILD_TYPE release) in my x64-linux.cmake triplets file, then I get this error:

-- Building x64-linux-rel
CMake Error at ports/liblas/portfile.cmake:41 (file):
  file COPY cannot find
  "/home/pmiller/pub/cpp/vcpkg-jackboosy/packages/liblas_x64-linux/debug/share/cmake/libLAS/liblas-depends-debug.cmake".
Call Stack (most recent call first):
  scripts/ports.cmake:85 (include)


Error: Building package liblas:x64-linux failed with: BUILD_FAILED
Please ensure you're using the latest portfiles with `.\vcpkg update`, then
submit an issue at https://github.com/Microsoft/vcpkg/issues including:
  Package: liblas:x64-linux
  Vcpkg version: 2019.08.23-unknownhash

Should be a new issue or can I tack it onto this one?

[JackBoosY]

@pwm1234 Nope, I will fix it in this PR.

[JackBoosY]

@pwm1234 Could you re-test it? Thanks.