Add s390x to call ABI compliant.
MIR compiles `c2m` sources again and generate another binary
MIR, and the two binary MIR files are identical
* The bootstrap test takes about CPU 10 sec (for comparison GCC minimal bootstrap takes about 2 CPU hours)
- * Full call ABI (multiple return regs, passing structures through regs) has implemented for aarch64
+ * ABI compliant calls (multiple return regs, passing structures through regs) has implemented for aarch64, s390x
