cbrt() broken in AIX

I´m trying to install postgres 8.3.6 at AIX 5.3, and I got a declaration
error that I presume its related to this [1] thread.

Here´s some info:
- Bladecenter IBM JS22 - PowerPC_POWER6 quad 4GHZ 64 bits
- AIX 5.3.0
- Postgresql 8.3.6
- gcc version 4.2.0
- GNU Make 3.80

First I tryed to configure with no options, and then make throw this:

float.c:74: error: static declaration of 'cbrt' follows non-static declaration

After some googling, I find Bruce´s path back on 7.4, that removed my_cbrt trick.
So, I changed float.c to the old code (the whole HAVE_CBRT stuff),
and the declaration error was gone, but now I got this :

/usr/bin/ld -r -o SUBSYS.o access/SUBSYS.o bootstrap/SUBSYS.o
catalog/SUBSYS.o parser/SUBSYS.o commands/SUBSYS.o
executor/SUBSYS.o lib/SUBSYS.o libpq/SUBSYS.o main/SUBSYS.o
nodes/SUBSYS.o optimizer/SUBSYS.o port/SUBSYS.o postmaster/SUBSYS.o
regex/SUBSYS.o rewrite/SUBSYS.o storage/SUBSYS.o tcop/SUBSYS.o
tsearch/SUBSYS.o utils/SUBSYS.o ../../src/timezone/SUBSYS.o
../../src/port/libpgport_srv.a
../../src/backend/port/aix/mkldexport.sh SUBSYS.o . > postgres.imp

gcc -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Winline
-Wdeclaration-after-statement -Wendif-labels -fno-strict-aliasing
-fwrapv -L../../src/port -Wl,-blibpath:/usr/local/pgsql/lib:/usr/lib:/lib
access/SUBSYS.o bootstrap/SUBSYS.o catalog/SUBSYS.o parser/SUBSYS.o
commands/SUBSYS.o executor/SUBSYS.o lib/SUBSYS.o libpq/SUBSYS.o main/SUBSYS.o
nodes/SUBSYS.o optimizer/SUBSYS.o port/SUBSYS.o postmaster/SUBSYS.o
regex/SUBSYS.o rewrite/SUBSYS.o storage/SUBSYS.o tcop/SUBSYS.o tsearch/SUBSYS.o
utils/SUBSYS.o ../../src/timezone/SUBSYS.o ../../src/port/libpgport_srv.a
-Wl,-bE:../../src/backend/postgres.imp -lld -o postgres
ld: 0711-317 ERROR: Undefined symbol: .lrint
ld: 0711-317 ERROR: Undefined symbol: ._isnan
ld: 0711-317 ERROR: Undefined symbol: ._isinff
ld: 0711-317 ERROR: Undefined symbol: .sqrt
ld: 0711-317 ERROR: Undefined symbol: .tan
ld: 0711-317 ERROR: Undefined symbol: .sin
ld: 0711-317 ERROR: Undefined symbol: .cos
ld: 0711-317 ERROR: Undefined symbol: .atan2
ld: 0711-317 ERROR: Undefined symbol: .atan
ld: 0711-317 ERROR: Undefined symbol: .asin
ld: 0711-317 ERROR: Undefined symbol: .acos
ld: 0711-317 ERROR: Undefined symbol: .log10
ld: 0711-317 ERROR: Undefined symbol: .log
ld: 0711-317 ERROR: Undefined symbol: .exp
ld: 0711-317 ERROR: Undefined symbol: .floor
ld: 0711-317 ERROR: Undefined symbol: .pow
ld: 0711-317 ERROR: Undefined symbol: .ceil
ld: 0711-317 ERROR: Undefined symbol: ._isnanf
ld: 0711-317 ERROR: Undefined symbol: .rintf
ld: 0711-317 ERROR: Undefined symbol: .lrintf
ld: 0711-317 ERROR: Undefined symbol: .llrint
ld: 0711-317 ERROR: Undefined symbol: .llrintf
ld: 0711-317 ERROR: Undefined symbol: .sqrtf
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
collect2: ld returned 8 exit status
gmake[2]: *** [postgres] Error 1
gmake[2]: Leaving directory `/usr/src/postgresql-8.3.6/src/backend'
gmake[1]: *** [all] Error 2
gmake[1]: Leaving directory `/usr/src/postgresql-8.3.6/src'
gmake: *** [all] Error 2

What can I do next ?

[1] http://archives.postgresql.org/pgsql-patches/2003-05/msg00127.php

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