fail to include sys/proc.h in Solaris 10 - c++

Question

Here is the same code:
#include <sys/proc.h>
int main(){
return 0;
}
Here is the library:
ROHIT root#solaris-demo:/$ ls -ltr /usr/include/sys/proc.h
-rw-r--r-- 1 root bin 30063 Jan 11 2013 /usr/include/sys/proc.h
And here is the compilation result:
ROHIT root#solaris-demo:/var/tmp/$ gcc test.c
In file included from test.c:1:
/usr/include/sys/proc.h:367: error: syntax error before "klgrpset_t"
Can anyone help me to know the reason behind this error and possible fix?
Here is additional information regarding my compiler and OS version:
ROHIT root#solaris-demo:/var/tmp/$ which gcc
/usr/sfw/bin/gcc
ROHIT root#solaris-demo:/var/tmp/$
ROHIT root#solaris-demo:/var/tmp/$ gcc -v
Reading specs from /usr/sfw/lib/gcc/i386-pc-solaris2.10/3.4.3/specs
Configured with: /builds/sfw10-gate/usr/src/cmd/gcc/gcc-3.4.3/configure --prefix=/usr/sfw --with-as=/usr/sfw/bin/gas --with-gnu-as --with-ld=/usr/ccs/bin/ld --without-gnu-ld --enable-languages=c,c++ --enable-shared
Thread model: posix
gcc version 3.4.3 (csl-sol210-3_4-branch+sol_rpath)
ROHIT root#solaris-demo:/var/tmp/$
ROHIT root#solaris-demo:/var/tmp/$ uname -a
SunOS solaris-demo 5.10 Generic_147148-26 i86pc i386 i86pc
ROHIT root#solaris-demo:/var/tmp/$
ROHIT root#solaris-demo:/var/tmp/$ cat /etc/release
Oracle Solaris 10 8/11 s10x_u10wos_17b X86
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