Overriding the optimisation flags under Win32 seems to be wrong.

In particular, according to bulk88, -W4 is never used on Win32, and produces
huge numbers of spurious warnings from perl library headers and etc.

I do not know where these build options come from, they look cargo culted to me.
change SRL_INLINE to SRL_STATIC_INLINE and define it properly on Win32

These terms are not portable. Win32 for instance considers "inline" to
be a post C89 addition and as such it is spelled __inline. Perl defines
various macros for this purpose, so we could use them instead and avoid
any portability issues - except that PERL_STATIC_INLINE *isn't* defined
as far as I can tell. Which means we have to fake our own. This might
need more refinement for exotic platforms, and etc.

Many thanks to bulk88 for the Win32 guidance.
Fix declaration after code bug which breaks C89

More thanks to bulk88 for flushing this issue out.
add a typedef for Win32 to csnappy_internal_userspace.h
fixup declaration after code C89 violation
s/\\bERROR/SRL_ERROR/g so we do not not collide with Win32 Macros

Seems like ERROR() is already a macro in Win32 land:

    c:\Documents and Settings\Owner\Desktop\cpanlibs\Sereal-Decoder-0.25\srl_decoder.h(51) : warning C4005: 'ERROR' : macro redefinition
    C:\Program Files\Microsoft Visual Studio .NET2003\Vc7\PlatformSDK\Include\WinGDI.h(98) : see previous definition of 'ERROR'

So we redefine them to be SRL_ERROR() to avoid conflicts. This is
just good housekeeping anyway.