Use <sys/select.h> to get select

POSIX mandates that select is declared in <sys/select.h> (and in the header
<sys/time.h> for compatibility). It would be best to include the new header
if it is available. This is already done throughout the source tree, though
not in all instances.

This change is released under the MIT/X11 license.
Use <poll.h> to get poll rather than <sys/poll.h>

POSIX specifies <poll.h> as the standard header that declares the poll
function. Many systems provide <sys/poll.h> to be compatible with historical
practice. Prefer the <poll.h> header over <sys/poll.h> if it is available.

This change is released under the MIT/X11 license.
Only include the <sys/param.h> header if available

The <sys/param.h> header is non-standard and usually not required if it isn't
available.

This change is released under the MIT/X11 license.
Remove unnecessary <sys/syscall.h> inclusion

Only mono/metadata/icall.c and mono/metadata/filewatcher.c include the
mono/metadata/filewatcher.h header and none of them depend on the contents
of the non-standard header <sys/syscall.h>.

This change is released under the MIT/X11 license.
Get struct timespec from <time.h> in mono/io-layer/misc-private.h

POSIX defines struct timespec in time.h and struct timeval in sys/time.h.
Some operating systems have merged these headers, but this isn't required or
encouraged by POSIX.

This change is released under the MIT/X11 license.
Use S_IWUSR instead of S_IWRITE

The S_IWRITE macro is a non-standard macro provided by some operating
systems for compatibility with BSD. POSIX specifics a standard macro with
identical semantics with the name S_IWUSR.

This change is released under the MIT/X11 license.
Avoid unused function warning in mono/io-layer/io.c

The get_fstypename function is only used by the GetVolumeInformation
function. It should be wrapped in the same #if conditional to avoid a
warning if the preprocessor conditional isn't true.

This change is released under the MIT/X11 license.
Avoid unused function warning in mono/profiler/proflog.c

The dump_ubin function is only used by the elf_dl_callback function. It
should be wrapped in the same #if conditional to avoid a warning if the
preprocessor conditional isn't true.

This change is released under the MIT/X11 license.
Use MAP_FAILED instead of (void*)-1

The MAP_FAILED macro is the standard return value of mmap() upon failure and
it is allowed to have other values than (void*)-1.

This change is released under the MIT/X11 license.
Remove MONO_SIZEOF_SUNPATH

The configure script determines the size of the sun_path member in struct
sockaddr_un. However the test is broken during cross-compilation (with a
comment that there is no macro to determine the size of struct members at
configure time) and MONO_SIZEOF_SUNPATH defaults to 0 (leading to buffer
underflows and overflows). There is no reason to determine this at configure
time when a simple traditional sizeof will do the job at compile time.

This change is released under the MIT/X11 license.
Use memset instead of bzero

There is no standard bzero function, only the standard memset function, and
Mono does not declare its own bzero function.

This change is released under the MIT/X11 license.
Use SIGPROF only if it is available

The SIGPROF signal is an XSI option and obsolescent in XSI. POSIX systems
are not required to have it.

This change is released under the MIT/X11 license.
Don't touch internal feature macros in eglib

The __USE_GNU macro is an internal macro used by glibc to enable the GNU
extensions. Programs are instead meant to use the _GNU_SOURCE macro before
including any system header.

This change is released under the MIT/X11 license.
Remove test whether thread-local storage works in shared libraries

This test was added in 2004 to work around buggy Linux distributions and is
not needed today. The test caused problems as it also ran on non-Linux
operating systems and assumed dynamic linking was available. This caused it
to mistakenly decide thread-local storage was unavailable on operating
systems with no dynamic linking (but perfectly usable thread-local storage).

This change is released under the MIT/X11 license.
Remove Mono_Posix_Syscall_utimes_bad

Welcome to the world of tomorrow! It's been almost a decade since this was
made obsolete in 2005. Nothing uses this function any longer. Additionally
it is completely broken as utimes takes a pointer to an array with two
timevals, but the code passes only a pointer to a single timeval.

This change is released under the MIT/X11 license.
Restore the null garbage collector

I had to use the null garbage collector due to boehm being troublesome. The
code appears unmaintained but I can see a recent git commit enabled support
again. However, I had to do more than that to get it working. I'm really not
sure how semantically correct this is and it needs review from an expert in
how threads and garbage collection interplay in Mono. It seems very odd that
various attributes (such as its short id) about the main thread is
initialized as a side effect of initializing the garbage collection. The
mono_thread_info_attach was needed to prevent a crash.

This change is released under the MIT/X11 license.