message: core: get rid of termios2, use termios on Linux
  In order to simplify and to enable the build in manylinux1 it makes
  sense to go back to termios instead of termios2.
diff: #include "global_include.h"
  #include "log.h"
  -#if defined(LINUX)
  -#include <unistd.h>
  -#include <fcntl.h>
  -#include <asm/ioctls.h>
  -#include <asm/termbits.h>
  -#include <sys/ioctl.h>
  -
  -#elif defined(APPLE)
  +#if defined(APPLE) || defined(LINUX)
  #include <unistd.h>
  #include <fcntl.h>
  #include <termios.h>
  @@ -115,16 +108,7 @@ ConnectionResult SerialConnection::setup_port()
  }
  #endif
  -#if defined(LINUX)
  - struct termios2 tc;
  - bzero(&tc, sizeof(tc));
  -
  - if (ioctl(_fd, TCGETS2, &tc) == -1) {
  - LogErr() << "Could not get termios2 " << GET_ERROR();
  - close(_fd);
  - return ConnectionResult::CONNECTION_ERROR;
  - }
  -#elif defined(APPLE)
  +#if defined(LINUX) || defined(APPLE)
  struct termios tc;
  bzero(&tc, sizeof(tc));
  @@ -146,26 +130,7 @@ ConnectionResult SerialConnection::setup_port()
  tc.c_cc[VTIME] = 0; // We don't timeout but wait indefinitely.
  #endif
  -#if defined(LINUX)
  - // CBAUD and BOTHER don't seem to be available for macOS with termios.
  - tc.c_cflag &= ~(CBAUD);
  - tc.c_cflag |= BOTHER;
  -
  - tc.c_ispeed = _baudrate;
  - tc.c_ospeed = _baudrate;
  -
  - if (ioctl(_fd, TCSETS2, &tc) == -1) {
  - LogErr() << "Could not set terminal attributes " << GET_ERROR();
  - close(_fd);
  - return ConnectionResult::CONNECTION_ERROR;
  - }
  -
  - if (ioctl(_fd, TCFLSH, TCIOFLUSH) == -1) {
  - LogErr() << "Could not flush terminal " << GET_ERROR();
  - close(_fd);
  - return ConnectionResult::CONNECTION_ERROR;
  - }
  -#elif defined(APPLE)
  +#if defined(LINUX) || defined(APPLE)
  tc.c_cflag |= CLOCAL; // Without this a write() blocks indefinitely.
  cfsetispeed(&tc, _baudrate);
  