The function value_from_host_double can be moved from f-lang.c into
value.c as a generally useful function, and then used more widely.
Tested on X86-64/GNU Linux with no regressions.
gdb/ChangeLog:
* f-lang.c (value_from_host_double): Moved to...
* value.c (value_from_host_double): ...here.
* value.h (value_from_host_double): Declare.
* guile/scm-math.c (vlscm_convert_typed_number): Use
value_from_host_double.
(vlscm_convert_number): Likewise.
* guile/scm-value.c (gdbscm_value_to_real): Likewise.
* python/py-value.c (convert_value_from_python): Likewise.