Fix delete operator redirection if gc_cpp is built as .dll (Cygwin, MinGW)

Fix delete operator redirection if gc_cpp is built as .dll (Cygwin, MinGW)

Issue #229 (bdwgc).

* include/gc_cpp.h [(__CYGWIN32__ || __CYGWIN__ || __MINGW32__)
&& !GC_BUILD && !GC_NOT_DLL && GC_OPERATOR_NEW_ARRAY] (operator new[],
operator delete[]): Define inline function.
* include/gc_cpp.h [(__CYGWIN32__ || __CYGWIN__ || __MINGW32__)
&& !GC_BUILD && !GC_NOT_DLL] (operator new, operator delete): Likewise.
* include/gc_cpp.h [_MSC_VER || __DMC__ || (__CYGWIN32__ || __CYGWIN__
|| __MINGW32__) && !GC_BUILD && !GC_NOT_DLL && __cplusplus>201103L]
(operator delete(void*,size_t)): Likewise.
* include/gc_cpp.h [_MSC_VER || __DMC__ || (__CYGWIN32__ || __CYGWIN__
|| __MINGW32__) && !GC_BUILD && !GC_NOT_DLL && __cplusplus>201103L
&& GC_OPERATOR_NEW_ARRAY && !CPPCHECK]
(operator delete[](void*,size_t)): Likewise.
* include/gc_cpp.h (operator new(size_t, int, const char*, int),
operator new[](size_t, int, const char*, int)): Do not define
for __DMC__.