linux-user: Fix mips fp64 executables loading

If a program requires fr1, we should set the FR bit of CP0 control status
register and add F64 hardware flag. The corresponding `else if` branch
statement is copied from the linux kernel sources (see `arch_check_elf` function
in linux/arch/mips/kernel/elf.c).

Signed-off-by: Daniil Kovalev <dkovalev@compiler-toolchain-for.me>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <20230404052153.16617-1-dkovalev@compiler-toolchain-for.me>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/mips/cpu_loop.c

@@ -290,7 +290,10 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
             env->CP0_Status |= (1 << CP0St_FR);
             env->hflags |= MIPS_HFLAG_F64;
         }
-    } else  if (!prog_req.fre && !prog_req.frdefault &&
+    } else if (prog_req.fr1) {
+        env->CP0_Status |= (1 << CP0St_FR);
+        env->hflags |= MIPS_HFLAG_F64;
+    } else if (!prog_req.fre && !prog_req.frdefault &&
           !prog_req.fr1 && !prog_req.single && !prog_req.soft) {
         fprintf(stderr, "qemu: Can't find a matching FPU mode\n");
         exit(1);