os2: disable visibility attribute

On OS/2, visibility attribute is not supported.

Author: komh

CMakeLists.txt

@@ -39,9 +39,12 @@ if(BUILD_TESTS)
   endif()
 endif()
 
-set(CMAKE_C_VISIBILITY_PRESET hidden)
-set(CMAKE_CXX_VISIBILITY_PRESET hidden)
-set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
+# On OS/2, visibility attribute is not supported.
+if(NOT OS2)
+  set(CMAKE_C_VISIBILITY_PRESET hidden)
+  set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+  set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
+endif()
 
 set(CMAKE_CXX_WARNING_LEVEL 4)
 if(NOT MSVC)
@@ -57,8 +60,8 @@ add_library(cubeb
   src/cubeb_log.cpp
   src/cubeb_strings.c
    $<TARGET_OBJECTS:speex>)
-target_include_directories(cubeb 
-  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include> 
+target_include_directories(cubeb
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:include>
 )
 target_include_directories(cubeb PRIVATE src)
 target_compile_definitions(cubeb PRIVATE OUTSIDE_SPEEX)
@@ -70,7 +73,7 @@ add_sanitizers(cubeb)
 
 include(GenerateExportHeader)
 generate_export_header(cubeb EXPORT_FILE_NAME ${CMAKE_BINARY_DIR}/exports/cubeb_export.h)
-target_include_directories(cubeb 
+target_include_directories(cubeb
   PUBLIC $<BUILD_INTERFACE:${CMAKE_BINARY_DIR}/exports>
 )
 
@@ -90,7 +93,7 @@ configure_package_config_file(
 )
 
 install(TARGETS cubeb
-  EXPORT "${PROJECT_NAME}Targets" 
+  EXPORT "${PROJECT_NAME}Targets"
   DESTINATION ${CMAKE_INSTALL_PREFIX}
   LIBRARY DESTINATION "lib"
   ARCHIVE DESTINATION "lib"