UnitTest++ not compiling with PGI compiler #153

Dear John,

UnitTest++ does not compile why the PGI compiler (latest Community edition) under Linux due to the following reason. In the CMakeLists.txt file at line 36 you define
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror")
which works well for Clang and GNU but is unsupported by the PGI compiler. I suggest to add

# up warning level for project
if (${UTPP_AMPLIFY_WARNINGS})
# instead of getting compiler specific, we're going to try making an assumption that an existing /W
# means
# we are dealing with an MSVC or MSVC-like compiler (e.g. Intel on Windows)
if(CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
string(REGEX REPLACE "/W[0-4]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /WX")
elseif(CMAKE_CXX_COMPILER_ID MATCHES "AppleClang" OR
CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR
CMAKE_CXX_COMPILER_ID MATCHES "GNU")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror")
elseif(CMAKE_CXX_COMPILER_ID MATCHES "PGI")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
endif()
endif()

Best regards,
Matthias