add -pthread to Compaq C++ invocation

[SVN r11144]

status/compiler.cfg

@@ -189,8 +189,8 @@ GNU<br><a href="http://gcc.gnu.org/">GCC</a><br>3.0.1
 tru64
 cxx
 Compaq C++ 6.3
-cxx -c -std strict_ansi -D__USE_STD_IOSTREAM -I%include %source
-cxx -o boosttmp.exe -std strict_ansi -D__USE_STD_IOSTREAM -I%include %source -lm
+cxx -c -std strict_ansi -D__USE_STD_IOSTREAM -pthread -I%include %source
+cxx -o boosttmp.exe -std strict_ansi -D__USE_STD_IOSTREAM -pthread -I%include %source -lm
 <a href="http://www.compaq.com/products/software/compilers/candcxx.html">Compaq C++</a><br>6.3-012
 
 // MIPSpro warnings that were turned off