[lldb-server] Remove dead CMake code

No files in lldb-server are including a header from a plugin without the
whole path to the header relative to the lldb source directory. There is
no need to include the specific directories as a result.

Author: bulbazord

lldb/tools/lldb-server/CMakeLists.txt

@@ -1,27 +1,3 @@
-if ( CMAKE_SYSTEM_NAME MATCHES "Linux" )
-include_directories(
-  ../../../../llvm/include
-  ../../source/Plugins/Process/Linux
-  ../../source/Plugins/Process/POSIX
-  )
-endif ()
-
-if ( CMAKE_SYSTEM_NAME MATCHES "FreeBSD" )
-include_directories(
-  ../../../../llvm/include
-  ../../source/Plugins/Process/FreeBSD
-  ../../source/Plugins/Process/POSIX
-  )
-endif ()
-
-if ( CMAKE_SYSTEM_NAME MATCHES "NetBSD" )
-include_directories(
-  ../../../../llvm/include
-  ../../source/Plugins/Process/NetBSD
-  ../../source/Plugins/Process/POSIX
-  )
-endif ()
-
 include_directories(../../source)
 
 set(LLDB_PLUGINS)