tx19 and related necessary changes.
* config.sub: Add tx19/r1900.
* sim/mips/configure.in, sim/mips/gencode: Add tx19/r1900.
* gcc/config.sub, gcc/configure: Add tx19/r1900.
* gcc/config/mips/r1900.h, config/mips/t-r1900: New.
* gas/config/tc-mips.c: Add tx19/r1900.
* gcc/config/mips/mips.c: Don't build 16 bit to 32 bit stubs for
TARGET_SOFT_FLOAT.
* config.sub: Add "marketing-names" patch.
* gcc/config.sub: Add "marketing-names" patch.
* gcc/configure: Change "as" link from "../gas/as.new" to "../gas/as-new";
Same for "ld" link.