BUG #2325: fails to compile with undefined symbol (FP_PLUS_INF)

The following bug has been logged online:

Bug reference: 2325
Logged by: Riccardo
Email address: multix79(at)yahoo(dot)com
PostgreSQL version: 8.1.3
Operating system: AIX 4.2.1
Description: fails to compile with undefined symbol (FP_PLUS_INF)
Details:

when compiling using gcc 3.4.5 I get the following error:

gcc -O2 -Wall -Wmissing-prototypes -Wpointer-arith -Winline
-Wdeclaration-after-statement -Wendif-labels -fno-strict-aliasing
-I../../src/port -DFRONTEND -I../../src/include -I/usr/local/include -c
isinf.c -o isinf.o
isinf.c: In function `isinf':
isinf.c:69: error: `FP_PLUS_INF' undeclared (first use in this function)
isinf.c:69: error: (Each undeclared identifier is reported only once
isinf.c:69: error: for each function it appears in.)
isinf.c:71: error: `FP_MINUS_INF' undeclared (first use in this function)
make[2]: *** [isinf.o] Error 1

configure options where:
./configure --with-includes=/usr/local/include --with-libs=/usr/local/lib
--without-readline