fix(aarch64-msvc support): include path for UnicodeCLib in lakefile

[SrGaabriel]

I got this error message in my aarch64-pc-windows-msvc system and this PR fixes it at no cost for other systems:

✖ [236/239] Building UnicodeBasic/UnicodeCLib
trace: .> cc -c -o C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\.lake\build\UnicodeCLib\case.o C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\UnicodeCLib\case.c -I c:\Users\gaabr\.elan\toolchains\leanprover--lean4---v4.28.0\include -O -fPIC
info: stderr:
C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\UnicodeCLib\case.c:2:10: fatal error: basic.h: No such file or directory
    2 | #include "basic.h"
      |          ^~~~~~~~~
compilation terminated.
error: external command 'cc' exited with code 1
trace: .> cc -c -o C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\.lake\build\UnicodeCLib\prop.o C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\UnicodeCLib\prop.c -I c:\Users\gaabr\.elan\toolchains\leanprover--lean4---v4.28.0\include -O -fPIC
info: stderr:
C:\Users\gaabr\Developer\soma\souls\.lake\packages\UnicodeBasic\UnicodeCLib\prop.c:2:10: fatal error: basic.h: No such file or directory
    2 | #include "basic.h"
      |          ^~~~~~~~~
compilation terminated.
error: external command 'cc' exited with code 1
Some required targets logged failures:
- UnicodeBasic/UnicodeCLib
error: build failed

[fgdorais]

Thanks!