windows warnings

I have just noticed the following warnings on currawong (MSVC):

"d:\bf\root\HEAD\pgsql.1748\pgsql.sln" (default target) (1) ->
(postgres target) ->
.\src\backend\utils\adt\array_selfuncs.c(574): warning C4305: '=' : truncation from 'double' to 'float4'
.\src\backend\optimizer\path\costsize.c(1911): warning C4013: '_isnan' undefined; assuming extern returning int
d:\bf\root\head\pgsql.1748\src\backend\catalog\objectaddress.c(1363): warning C4715: 'get_object_property_data' : not all control paths return a value

"d:\bf\root\HEAD\pgsql.1748\pgsql.sln" (default target) (1) ->
(interfaces\libecpg target) ->
d:\bf\root\head\pgsql.1748\src\interfaces\ecpg\ecpglib\typename.c(68): warning C4715: 'ecpg_type_name' : not all control paths return a value

I think we can fix the first by doing a cast to float4, the second by
#including float.h, and the third and fourth by adding return statements
at the bottom of the functions which won't in fact ever be reached. but
should keep the compiler happy.

There are also a bunch of warnings like this from the python include
files that I guess we can't do much about, unfortunately (it's
re-typdefing ssize_t):

"d:\bf\root\HEAD\pgsql.1748\pgsql.sln" (default target) (1) ->
(PLs\plpython2 target) ->
c:\python27\include\pyconfig.h(201): warning C4142: benign redefinition of type

cheers

andrew