No need for runtime_srcdir.
Merge pull request #294 from waywardmonkeys/c-run-time-build

C run time build
Fix references to Linux.

Fixes #296.
Use gcc primitives instead of x86 asm for interlocked ops.

This also generates better code.

Fixes #297.
For now, just use this on all Unix platforms.

This should be something else, like C code or a check for x86, but
we can deal with that when we want to do something other than x86
support in this runtime.
Remove X86_LINUX_PLATFORM define that is not used.
Inline the atomic ops functions.
Remove unused defines.
Switch tlv_writer_counter to standard C types.
Remove some Windows typedefs from Unix port.
Use pthread_t rather than HANDLE.
Missing type specification.
Stop using deprecated pthread_mutexattr_setkind_np.

This was deprecated more than 10 years ago in favor of
pthread_mutexattr_settype.
Fix subsequence-position-7.  Change some check-true to check-equal.
Remove Boehm runtime build on Windows.
Remove unused mmtuneflags from Windows runtime build.
Remove unused boehm-collector support file.
simple-object-vector-instance => vector
BOEHM_GC preprocessor flag -> GC_USE_BOEHM.

GC_USE_BOEHM is what our configure script will handle.
Fix sequences-element-id?.