New utility rz-ar to unpack .a and .lib files

[wargio]

When you try to unpack windows built static libraries (.a and .lib) with ar x file.a it will fail due the path not being available.

Moreover there are "valid" and "invalid" libraries built by the windows sdk which can and cannot have object files.

rz-ar should be able create the needed subfolder and unpack the object files in the working directory (unless an output dir is specified).

This new utility will be beneficial for creating signatures and more.

Example:

$ rizin -qc 'ol' ar://valid-BufferOverflow.lib 
 3 * r-x 0x0000424a ar://valid-BufferOverflow.lib//d_/8180.public.fre/internal/minwin/priv_sdk/lib/amd64/loadcfg.obj
 4 - r-x 0x00004249 ar://valid-BufferOverflow.lib//d_/8180.public.fre/internal/minwin/priv_sdk/lib/amd64/guard_support.obj
 5 - r-x 0x0000d645 ar://valid-BufferOverflow.lib//e_/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/gs_dllmain.obj
 6 - r-x 0x0000fc91 ar://valid-BufferOverflow.lib//e_/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/gs_support.obj
 7 - r-x 0x00000658 ar://valid-BufferOverflow.lib//e_/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/amdsecgs.obj
$ ar tv valid-BufferOverflow.lib 
r--r--r-- 100444/100444  16970 Feb 27 07:34 2015 d:/8180.public.fre/internal/minwin/priv_sdk/lib/amd64/loadcfg.obj
r--r--r-- 100444/100444  16969 Feb 27 07:34 2015 d:/8180.public.fre/internal/minwin/priv_sdk/lib/amd64/guard_support.obj
rw-rw-rw- 100666/100666  54853 Feb 27 07:36 2015 e:/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/gs_dllmain.obj
rw-rw-rw- 100666/100666  64657 Feb 27 07:36 2015 e:/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/gs_support.obj
rw-rw-rw- 100666/100666   1624 Feb 27 07:36 2015 e:/8180.obj.amd64fre/minkernel/tools/gs_support/ntdll/objfre/amd64/amdsecgs.obj
$ ar tv invalid-audioeng.lib 
--------- 0/0    498 Aug 22 16:03 2013 audioeng.dll
--------- 0/0    251 Aug 22 16:03 2013 audioeng.dll
--------- 0/0    288 Aug 22 16:03 2013 audioeng.dll
--------- 0/0     47 Aug 22 16:03 2013 audioeng.dll
--------- 0/0     43 Aug 22 16:03 2013 audioeng.dll
$ rizin -qc 'ol' ar://invalid-audioeng.lib 
ERROR: Cannot open 'ar://invalid-audioeng.lib'

examples.zip