Exclude failing "complex.h" test on Windows, where old MSVC versions lack...

Exclude failing "complex.h" test on Windows, where old MSVC versions lack "<complex.h>" entirely and more recent versions fail to compile the test.

tests/windows_bugs.txt

@@ -29,3 +29,5 @@ lunch
 # "C linkage function cannot return C++ class" (uses public C++ cdef function)
 cpp_template_subclasses
 
+# MSVC lacks "complex.h"
+complex_numbers_cmath_T2891