You have to recompile the standard C library and add the path in your environment.
The library currently used in the project is available here: "Compiler\SH_COFF\sh-coff\sh-coff\lib\libc.a"
If you look closer into the "compile.bat script", you will see paths :
SET PATH=%COMPILER_DIR%\SH_COFF\Other Utilities;%COMPILER_DIR%\SH_COFF\sh-coff\bin;%COMPILER_DIR%\TOOLS;%PATH%
You will find in attachement the C library compiled (ELF Format) (old version but enough)