Since we now always build the library with cdecl calling conventions,
our callbacks should be decorated as such so that users will not be able
to provide callbacks defined with other calling conventions.

The `GIT_CALLBACK` macro will inject the `__cdecl` attribute as
appropriate.

To explicitly break end-users who were specifying STDCALL, explicitly
fail the cmake process to ensure that they know that they need to change
their bindings.  Otherwise, we would quietly ignore their option and the
resulting cdecl library would produced undefined behavior.

The recommendation from engineers within Microsoft is that libraries
should have a calling convention specified in the public API, and that
calling convention should be cdecl unless there are strong reasons to
use a different calling convention.

We previously offered end-users the choice between cdecl and stdcall
calling conventions.  We did this for presumed wider compatibility: most
Windows applications will use cdecl, but C# and PInvoke default to
stdcall for WINAPI compatibility.  (On Windows, the standard library
functions are are stdcall so PInvoke also defaults to stdcall.)

However, C# and PInvoke can easily call cdecl APIs by specifying an
annotation.

Thus, we will explicitly declare ourselves cdecl and remove the option
to build as stdcall.

The GIT_EXTERN macro needs to provide order-specific attributes; update
users of the GIT_DEPRECATED macro to allow for that.

changelog: document changes since 0.27

Fix a bunch of warnings

mailmap: prefer ethomson@edwardthomson.com

My @github.com address is no more.

Convert tests/resources/push.sh to LF endings

This changes that file to use UNIX line-endings, which makes sense since
this is a UNIXy file.

Get rid of some test files that were accidentally committed

Fix crash on remote connection when GIT_PROXY_AUTO is set but no proxy is detected

Make ENABLE_WERROR actually work

Remove unconditional -Wno-deprecated-declaration on macOS

After taking into consideration the following, I think this should be
removed :

- OpenSSL isn't the default on Apple platforms
- you have to jump through hoops to get CMake to use OpenSSL on macOS
(headers aren't in `/usr/include`, so you have to provide `-DOPENSSL_*`
overrides)
- users are likely (as getting anywhere near the installed 0.9.8 version
is insanity IMHO) to package a "modern" version, which wouldn't be
marked as deprecated

This change explicitly adds -Werror to the CFLAGS.

Due to the way that the ADD_C_FLAG_IF_SUPPORTED() macro was mangling the
flag name to convert it into a define name, any warning that had a dash
in its name was not being correctly enabled. Additionally, any flag that
is enabled implicitly by the compiler (like -Wunused-result and
-Wdeprecated-declarations) would not cause an error unless they were
explicitly enabled with the ENABLE_WARNINGS() macro.

Fix warning 'function': incompatible types - from 'git_cvar_value *' to 'int *' (C4133) on VS

Fix Linux warnings

Less controversial changes together is better.

This change fixes -Wmaybe-uninitialized and -Wdeprecated-declarations
warnings on Linux builds

Coverity fixes

Signed-off-by: Sven Strickroth <email@cs-ware.de>

It seems like MingW64's size_t is defined differently than in Linux.

This change fixes a bunch of warnings that were discovered by compiling
with `clang -target=i386-pc-linux-gnu`. It turned out that the
intrinsics were not necessarily being used in all platforms! Especially
in GCC, since it does not support __has_builtin.

Some more warnings were gleaned from the Windows build, but I stopped
when I saw that some third-party dependencies (e.g. zlib) have warnings
of their own, so we might never be able to enable -Werror there.

Coverity considers that anything that looks like assert() behaves like
it (ie. side-effects would be skipped on a NDEBUG build). As we have a
bunch of those in the test suite (128), this would ensure Coverity isn't
confused.

CID 1398597, 1398598

CID 1382962

CID 1386176, 1386177, 1388219

Previously, an error in `git_config_next` would be mistaken as a
successful load, because the previous call would have succeeded.
Coverity saw the subsequent check for a completed iteration as dead, so
let's make it useful again.

CID 1391374

CID 1395011