libgcrpyt 1.12.2 compile IBM POWER AIX

Hello,

with this library I am having more troubles.
Last time I compiled with XL cc (xlC) compiler.

This currently results in two issues:
1) the -Werror flag is not supported.
According to the IBM documentation it is a xlclang/++ flag
For xlc/xlC it should be -qhalt. Which would also work for xlclang/++.
2) cc need the flag -qtls to support __thread storage class
xlclang would do this without

If I try to compile with xlclang I get several warnings
    option '-fno-delete-null-pointer-checks' is not supported
And an error at
    Assembler:
    .libs/mpi-inline$1.s: line 48: invalid opcode or pseudo-op
       1500-067: (S) asm statement generates error in assembler output.

What is the intended way to compile the library xlC or xlclang?
Unless somebody can point out a fix for the assembler error I will for 
now proceede to remove -Werror and add my '-qtls' option.

Best regards
     Frank