Fix name conflicts with small macro from rpcndr

[tobiasdiez]

On Windows, if you include windows.h then you get the following error

C:/Users/Tobia/.conda/envs/sage-dev/Library/include\flint/qsieve.h(66): error C2059: syntax error: 'type'
C:/Users/Tobia/.conda/envs/sage-dev/Library/include\flint/qsieve.h(69): error C2059: syntax error: '}'

since small is defined as a macro (see eg https://stackoverflow.com/questions/27793470/why-does-small-give-an-error-about-char). To fix this, small is undefined before its used as a variable name.

[albinahlback]

Good catch!

[albinahlback]

Thanks!