problem compiling SparseCmplxQR.cc with a RHEL3 box

[Cohen-Tanugi, Johann]

hi,
I am getting the following compile error trying to build octave 2.9.10 on an 
RHEL3 box :
-bash-2.05b$ gmake
g++ -c  -fPIC -I. -I.. -I../liboctave -I../src -I../libcruft/misc   
-DHAVE_CONFIG_H -mieee-fp -Wall -W -Wshadow -Wold-style-cast -g -O2 
SparseCmplxQR.cc -o pic/SparseCmplxQR.o
SparseCmplxQR.cc:40: syntax error before `__attribute__'
...
and then a bunch of warnings.

-bash-2.05b$ uname -a
Linux noric02 2.4.21-47.0.1.ELsmp #1 SMP Fri Oct 13 17:47:16 EDT 2006 i686 
athlon i386 GNU/Linux


the line 40 of the file is :
SparseComplexQR::SparseComplexQR_rep::SparseComplexQR_rep 
(const SparseComplexMatrix& a GCC_ATTR_UNUSED,                     
<----------this line
 int order GCC_ATTR_UNUSED)

so I am stuck as to debugging what goes wrong....

thanks for your help,
Johann