* device/lib/z80/mul.s (__mulsuchar_rrx_s, __muluschar_rrx_s),

* device/lib/z80/div.s (__divsuchar_rrx_s, __modsuchar_rrx_s,
  __divuschar_rrx_s, __moduschar_rrx_s): added mixed signedness versions
* device/lib/z80/stubs.s: added stubs for above functions
* src/SDCCopt.c (convilong),
* src/SDCCsymt.c (initCSupport): fixed bug 1900961
* src/SDCCsymt.h (__muldiv): enlarged for mixed signedness
* src/z80/main.c (_hasNativeMulFor): fixed bug, I think
* support/regression/tests/onebyte.c: enabled all tests for z80

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@5241 4a8a32a2-be11-0410-ad9d-d568d2c75423