simpleperf: check if dwarf callgraph is supported by kernel before testing.

Move inclusion of poll.h from header files to source files,
as event_selection_set.h is used by cmd_report_test.cpp, which
can be built on windows.

Bug: 27590546
Change-Id: Ic6b141a93d96610f911ab52da1d927b7f619ccb2
5 files changed