* ansidecl.h: Add extern "C" when compiling with C++.  Treat C++
	the way we treat an ISO C compiler.  Don't define inline as a
	macdro when compiling with C++.
	* dyn-string.h: Add header guard DYN_STRING_H.  Add extern "C"
	when compiling with C++.
	* fibheap.h: Add extern "C" when compiling with C++.

From-SVN: r148032