VM may crash at startup because StdoutLog/StderrLog logging stream can be badly aligned

Change "8146009: "pure virtual method called" with using new GC logging mechanism" introduced a sophisticated initialization mechanism for the logging stream. In order to avoid deconstruction of the streams before the VM exits, it creates them with a placement new into statically allocated memory:

static bool initialized;
static char stdoutmem[sizeof(LogStdoutOutput)];
static char stderrmem[sizeof(LogStderrOutput)];

LogStdoutOutput &StdoutLog = reinterpret_cast<LogStdoutOutput&>(stdoutmem);
LogStderrOutput &StderrLog = reinterpret_cast<LogStderrOutput&>(stderrmem);

LogFileStreamInitializer::LogFileStreamInitializer() {
  if (!initialized) {
    ::new (&StdoutLog) LogStdoutOutput();
    ::new (&StderrLog) LogStderrOutput();
    initialized = true;
  }
}

Unfortunately it is not guaranteed, that the static memory (which is a char array) is well-aligned for the stream objects. Actually, the C++ standard only defines that it has to be at least 'char' aligned which is obviously not enough for a stream object.
When building 'slowdebug' on Solaris with SS12u4 we indeed observed reproducible crashes during VM initialization because of this issue.

The fix is easy - just wrap the character arrays into unions to align them appropriately:

static union {
  char stdoutmem[sizeof(LogStdoutOutput)];
  void* dummy;
} aligned_stdoutmem;
static union {
  char stderrmem[sizeof(LogStderrOutput)];
  void* dummy;
} aligned_stderrmem;

LogStdoutOutput &StdoutLog = reinterpret_cast<LogStdoutOutput&>(aligned_stdoutmem.stdoutmem);
LogStderrOutput &StderrLog = reinterpret_cast<LogStderrOutput&>(aligned_stderrmem.stderrmem);