* gnu-regex.c: Eliminate obsolete check for _MSC_VER.

* gnu-regex.c: Eliminate obsolete check for _MSC_VER.
* utils.c (notice_quit): Remove dummy function only used for _MSC_VER.
* values.c (unpack_double): Remove obsolete check for _MSC_VER.
* defs.h: Ditto.
* m32r-rom.c: Ditto.
* p-exp.y: Ditto.
* ser-e7kpc.c: Ditto.  Define WIN32_LEAN_AND_MEAN under _WIN32, for faster
compilation.
(get_ds_base): Remove _MSC_VER version of this function.
* nindy-share/ttyflush.c: Ditto.  X
* rdi-share/host.h: Ditto.  X
* ser-go32.c (dos_readchar): Remove call to obsolete function.
* remote-sim.c (gdb_os_poll_quit): Ditto.
* remote-e7000.c (expect): Remove obsolete #if 0'ed code.
* main.c (captured_main): Eliminate special Cygwin checks.
* ser-tcp.c: Remove unneeded __CYGWIN__ guard against system include.