...and add a test.

The new argument is to make TTreeProcessorMT consistent with other
multi-threading interfaces, namely TThreadExecutor. This is the last
ingredient required to fix ROOT-10561.

Some builds might not be able to access files at root://eospublic.cern.ch

- Add a CMake flag (win_broken_tests) to enable broken tests on Windows
- Add a couple of `FIXME` comments, for the following errors:
  - In TSystem::GetIncludePath(), with ACLiC:
    input_line_12:8:38: error: use of undeclared identifier 'IC'
    "C:/Users/bellenot/build/debug/etc" -IC:/Users/bellenot/build/debug/etc//cling -IC:/Users/bellenot/build/debug/include"",
                                         ^
    Error in <ACLiC>: Dictionary generation failed!
  - When compiling math/mathmore/test/StatFunction.cxx, it generates those errors:
    Math/Functor.h(182): error C2059: syntax error: '<'
    Math/Functor.h(182): error C2947: expecting '>' to terminate template-argument-list, found '<'
    Math/Functor.h(182): error C2062: type 'unknown-type' unexpected
    Math/Functor.h(181,-1847264676) : error C2039: 'Clone': is not a member of '`global namespace''
    Math/Functor.h(182): error C2143: syntax error: missing ';' before '{'
    Math/Functor.h(182): error C2447: '{': missing function header (old-style formal list?)
    Math/Functor.h(182): error C2059: syntax error: '<'
    Math/Functor.h(182): error C2947: expecting '>' to terminate template-argument-list, found '<'
    Math/Functor.h(182): error C2062: type 'unknown-type' unexpected
    Math/Functor.h(181,-1847263020) : error C2039: 'Clone': is not a member of '`global namespace''
    Math/Functor.h(182): error C2143: syntax error: missing ';' before '{'
    Math/Functor.h(182): error C2447: '{': missing function header (old-style formal list?)

- Add a couple of missing symbols into the export list
- Fix several test failing on Windows, mostly due to files staying open (creates file access issues on Windows)
- Filter-out several unsupported tests (will add them back once the underlying issues are fixed)

"Last cluster in processed TTree is dropped under specific
circumstances"