Fixed t_mbsrtowcs_s.exe compilation under newer mingw gcc
mingw BOS needs now stdlib.h

See ChangeLog

Bump ABI revision to 3:6:0

See Changelog

Allow for manual definition of HAVE___SYNC_SYNCHRONIZE,
HAVE__MM_MFENCE, or HAVE__MM_SFENCE if the current compile-time
probes fail. This really should be put into configure (TODO).

some compilers have such a bad optimizer, that they cannot get the
object_size of static vars, like pgcc 17.4 and pgcc 19.4 on linux and
darwin. (nvidia)

Adjust the tests to detect that limitations.  In many cases we have now 3
different compiler-dependent results on overflows: msvcrt (different native secapi),
pgcc (no bos detection) and normal compilers with proper object_size
compile-time detection.

Closes #60

ignore the msys2 SECAPI. it does not honor MINGW_HAS_SECURE_API anymore.
link to our qsort_s and asctime_s implementations.

The -uni16 tables for windows has now overflows (-1) with indirection,
add code for that. Previously we only needed overflow _exc handling
for the compat tables. cperl had that code already, because utf8
had much longer entries.

This should fix the windows crashes.

use the gcc-4 builtin __sync_synchronize, not
ASM_VOLATILE("memory_barrier" ::: "memory"), which is documented to work,
but does not on the arm-linux-gnueabihf-gcc 8.3 cross compiler

bump so version in smoke.sh

with mkheader 1.26 from cperl-5.30

for a bit consistency

See ChangeLog

See ChangeLog

use 64bit copy on 64bit machines, not just 32bit.
memcpy_s is now as fast as memcpy native, with in overhead
of -1 to +3%, on clang-4+
gcc is only 77% slower, not 89%.

ESUNTERM for src to avoid overflows.

when the compiler knows the object_size (BOS), not ESLEMAX.
Does not work reliably for constant literal strings at compile-time,
but at run-time it mostly does.

Note: with -O2 the duplicated error blocks are merged with a simple goto/jmp.
Maybe we should do it explicitly.

warnings being treated as errors.
error: suggest a space before ';' or explicit braces around empty body in 'for' statement
disable -Werror then.

worse is that older g++ (4.3) do not permit
pragma gcc diagnostic inside functions at all.
so we add HAVE_CXX to our HAVE_C99 for this.

to be able to run the testsuite still.

we also test now wine-3.0, and add/clarify the recently added smokers

Wrong copy&paste constant

-mretpoline is currently the clang-7.0 name for Spectre mitigation.
gcc-7.3/8.1 branches currently use -mindirect-branch=thunk-extern for this.
The default GNU linker check does not work though, you need llvm lld-7.
so add -Wl,-z,retpolineplt only where the retpoline spectre option was added.
Without linker support don't add the cflags neither, but warn.
It needs lld-7 via LDFLAGS=-fuse-ld=lld-7

There is also a new -Wl,-z,textonly option.
https://sourceware.org/ml/binutils/2017-11/msg00369.html
Probe for it also.

as it is done on wine and msvcrt

use now the native vsnprintf_s function to reject illegal format
specifiers.
vsnprintf permits those.

Closes GH #45

change the slen=0 logic to match msvcrt and strncat_s.
only EOK when dest is valid.

and close #41

and skips the dllexport/dllimport attributes.
We can now build static-only on windows, which eases debugging

libtool sets the pic_flag -DDLL_EXPORT when building a shared lib on
windows, so we could have used that instead. But we need it later in test
executables to see if -lsafec is used at all, or overridden by -lc
dynamically when using shared libs. So we need it in the runtime config.
And with a different name.

- Fixed 32bit Windows wchar conversion functions, by changing wint_t to uint32_t
  types for most internal conversions.
- Changed 2 public APIs:
  int iswfc(uint32_t wc);
  int towfc_s(wchar_t *restrict dest, rsize_t dmax, const uint32_t src);
- Removed ssize_t GNU extension (jeremyhannon)
- Removed illegal warnings with C++
- Fixed tests failing with C++
- Fixed cygwin smokes on Appveyor
- Workaround broken gcc-4.8 strchr macro
- Probe for broken strnstr, broken in newlib until Aug 2017.
- Fixed mingw smokes on Appveyor, adjusted many tests using
  the native sec_api variants which do deviate from safeclib.
- Clear dest on empty src with *ncpy_s and *ncat_s: PR #38 (Arjun Gour)
- More hardening: Add -Wl,-z,noexecstack to AM_LDFLAGS,
  retpoline, textonly not yet.

Update run-time constraint violation checks.

handle_error already clears *dest.
clearing dest + invoke_safe_str_constraint_handler == handle_error()

add test cases.

prepare 3.2 release