Add requirements for Comeau toolset.

Fixes #3692. Patch from Mateusz Loskot.


[SVN r58027]

Jamroot

@@ -186,6 +186,9 @@ project boost
       # The standard library Sun compilers use by default has no chance
       # of working with Boost. Override it.
       <toolset>sun:<stdlib>sun-stlport
+      # Comeau does not support shared lib
+      <toolset>como:<link>static
+      <toolset>como-linux:<define>_GNU_SOURCE=1
     : usage-requirements <include>.
     : build-dir bin.v2
     ;