On my x86, I've a problem durning the link edition :
lib/built-in.o(.text+0x280): In function `qsort':
lib/qsort.c:87: multiple definition of `qsort'
fs/built-in.o(.text+0x12eac0):fs/xfs/support/qsort.c:79: first defined here
ld: Warning: size of symbol `qsort' changed from 1721 in fs/built-in.o 
to 1095 in lib/built-in.o
ld: final link failed: Memory exhausted
make: *** [.tmp_vmlinux1] Error 1

I don't understand why there are 2 qsorts files.
I have disabled the support of xfs to resolve the problem. I didn't want 
to change the name of the qsort implemented in fs/xfs/support/qsort.c or 
to delete this file :)

I include the .config