* Update libffi.rb

Old
```
crew files libffi
libffi: The libffi library provides a portable, high level programming interface to various calling conventions.
/usr/local/include/ffi.h
/usr/local/include/ffitarget.h
/usr/local/lib64/libffi.la
/usr/local/lib64/libffi.so
/usr/local/lib64/libffi.so.7
/usr/local/lib64/libffi.so.7.1.0
/usr/local/lib64/pkgconfig/libffi.pc
/usr/local/share/info/dir.gz
/usr/local/share/info/libffi.info.gz
/usr/local/share/man/man3/x86_64-cros-linux-gnu-ffi.3.gz
/usr/local/share/man/man3/x86_64-cros-linux-gnu-ffi_call.3.gz
/usr/local/share/man/man3/x86_64-cros-linux-gnu-ffi_prep_cif.3.gz
/usr/local/share/man/man3/x86_64-cros-linux-gnu-ffi_prep_cif_var.3.gz
Total found: 13
Disk usage: 90KB
```
new:
```
libffi: The libffi library provides a portable, high level programming interface to various calling conventions.
/usr/local/include/ffi.h
/usr/local/include/ffitarget.h
/usr/local/lib64/libffi.a
/usr/local/lib64/libffi.la
/usr/local/lib64/libffi.so
/usr/local/lib64/libffi.so.7
/usr/local/lib64/libffi.so.7.1.0
/usr/local/lib64/pkgconfig/libffi.pc
/usr/local/share/info/dir.gz
/usr/local/share/info/libffi.info.gz
/usr/local/share/man/man3/ffi.3.gz
/usr/local/share/man/man3/ffi_call.3.gz
/usr/local/share/man/man3/ffi_prep_cif.3.gz
/usr/local/share/man/man3/ffi_prep_cif_var.3.gz
Total found: 14
Disk usage: 324KB
```

* Update aria2.rb

* Update trousers.rb

* Update libmetalink.rb

* Update mono.rb

* Remove target prefix workaround logic

* Update aria2.rb

* Update libffi.rb

* Update libmetalink.rb

* Update mono.rb

* Update trousers.rb