Fix compatibility with msvc < 1400

Visual Studio .NET 2003, used by Python 2.5 32 bit, does not support the '__restrict' keyword.
This should be backported to the 0.19.x branch.
This fixes the following kind of compiler error:
```
building 'Cython.Compiler.Parsing' extension
C:\Program Files (x86)\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe /c /nologo /Ox /MD /W3 /GX /DNDEBUG -IX:\Python25\include -IX:\Python25\PC /TcCython\Compiler\Parsing.c /Fobuild\temp.win32-2.5\Release\Cython\Compiler\Parsing.obj Parsing.c
Cython\Compiler\Parsing.c(55967) : error C4235: nonstandard extension used : '__restrict' keyword not supported in this product
Cython\Compiler\Parsing.c(55967) : error C4235: nonstandard extension used : '__restrict' keyword not supported in this product
error: command '"C:\Program Files (x86)\Microsoft Visual Studio .NET 2003\Vc7\bin\cl.exe"' failed with exit status 2
```