Gnu make option to fix parallel multiple ar on a shared archive

[Navin P]

Hi,
   I ran multiple instances of ar during a parallel build and they were
updating different object files using ar rv sometimes the same object file
again.

When i run make -j1 i find all the object files  libx.a but when i do make
-j8 i find some missing object files inside libx.a.

Then i looked at ar.c and found that there is no synchronization between 2
instances of ar on same library. The problem is that makefile is generated
and  there are lots of bash scripts doing that.

Is there any way to fix the problem?
1. Without changing makefile
2. With changing the makefile in long term.

Regards,
Navin