fix compile warnings

When compiling with [-Wold-style-declaration] on GCC, this warning appears:

  warning: ‘inline’ is not at beginning of declaration

This is easily fixed moving the INLINE directive at the very beginning of the declaration
Merge branch 'master' of https://github.com/ctrix/libsodium
CMake support as an alternative to AutoTools

This commit adds support anddocumentation for a CMake build.

Everything supported by the autotools build should be present except the following differences:

- The test suite is not present

- The DEBUG build adds more checks (and more warnings at build time that will be addressed eventually)

- Removes some header checks that seems not to be used in the autotools (like emmintrin.h, tmmintrin.h ...)

- __STDC_LIMIT_MACROS is not tested

- enable_asm flag is supported but there is no C+asm build test

- for 128-bit arithmetic is supported and can be enabled but there is no build test support

- clock_gettime, fegetenv, SecureZeroMemory tests have been removed as those functions are used regardless their presence in the code.

I hope this will work for most people out there. CMake could even be used to build on Windows platforms.

Feedbacks are welcome.

Besides, i have noticed that the latest HEAD built with autotools has a version of 0.4.2 but
the soversion is 4.3. Is it correct ? (the cmake build system uses SODIUM_LIBRARY_VERSION_MAJOR
and SODIUM_LIBRARY_VERSION_MINOR to set the soversion file extension)