arrow

ARROW-4065: [C++] arrowTargets.cmake is broken

When we build Arrow's cpp library using CMake, arrowTargets.cmake will be generated and installed but it's broken.

The following is a part of arrowTargets.cmake generated.

```
# Create imported target arrow_shared
add_library(arrow_shared SHARED IMPORTED)

set_target_properties(arrow_shared PROPERTIES
  INTERFACE_LINK_LIBRARIES "dl;pthreadshared"
)

# Create imported target arrow_static
add_library(arrow_static STATIC IMPORTED)

set_target_properties(arrow_static PROPERTIES
  INTERFACE_LINK_LIBRARIES "glog_static;zstd_static;zlib_shared;snappy_static;lz4_static;brotli_dec_static;brotli_enc_static;brotli_common_static;double-conversion_static;boost_system_shared;boost_filesystem_shared;boost_regex_shared;jemalloc_static;rt;pthreadshared"
)
```

There are no INTERFACE_INCLUDE_DIRECTORIES and linker doesn't recognize pthreadshared because the true name of pthread should be libpthread.so or libpthread.a.
*_static and *_shared are also wrong name.

After this fix, we can build apps which links to arrow using CMake with CMakeLists.txt like as follows.

```
cmake_minimum_required(VERSION ...)
project(...)
...
find_package(arrow)
add_executable(your_excellent_app ...)
target_link_libraries(your_excellent_app arrow_shared) # or arrow_static
...
```

`$ cmake -D CMAKE_PREFIX_PATH=/path/to/arrow /path/to/CMakeLists.txt`
`$ cmake --build .`

Author: Kousuke Saruta <sarutak@oss.nttdata.com>

Closes #3212 from sarutak/improve-cmake-config-file-generation and squashes the following commits:

0213d2666 <Kousuke Saruta> Fix cpp/CMakeLists.txt, src/arrow/CMakeLists.txt and BuildUtils.cmake to enable building apps which links to Arrow using arrowTargets.cmake