IEEE half precision floats incomplete

[claziss]

The next dejagnu errors are extra added

FAIL: gcc.dg/torture/floatn-convert.c   -O0  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O1  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O2  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O3 -g  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -Os  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: gcc.dg/torture/floatn-convert.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (internal compiler error)
FAIL: gcc.dg/torture/floatn-convert.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)
FAIL: gcc.dg/torture/fp-int-convert-float16-timode.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (internal compiler error)
FAIL: gcc.dg/torture/fp-int-convert-float16-timode.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
FAIL: gcc.dg/torture/fp-int-convert-float16-timode.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (internal compiler error)
FAIL: gcc.dg/torture/fp-int-convert-float16-timode.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)

The are due to missing conversion routines from half-to-double precision fp.