RFR(XS): 8220660: [s390]: debug build broken after JDK-8220301

[Doerr, Martin]

Hi,

I'd like to fix an s390 debug build error introduced by JDK-8220301:
src/hotspot/cpu/s390/gc/g1/g1BarrierSetAssembler_s390.cpp: In member function 'void G1BarrierSetAssembler::g1_write_barrier_post(MacroAssembler*, DecoratorSet, Register, Register, Register, Register, Register)':
/usr/work/d056149/openjdk/jdk/src/hotspot/cpu/s390/gc/g1/g1BarrierSetAssembler_s390.cpp:319:57: error: comparison is always true due to limited range of data type [-Werror=type-limits]
   assert((unsigned int)G1CardTable::dirty_card_val() <= 255, "otherwise check this code");

This assertion is pointless since dirty_card_val is uint8_t.

Please review the removal of it:
http://cr.openjdk.java.net/~mdoerr/8220660_fix_s390_build/webrev.00/

Best regards,
Martin