Allow our headers to be included by C++ programs easily.

src/libeinfo/einfo.h

@@ -51,6 +51,8 @@
 # endif
 #endif
 
+__BEGIN_DECLS
+
 /*! @brief Color types to use */
 typedef enum
 {
@@ -141,4 +143,5 @@ void eoutdentv(void);
 /*! @brief Prefix each einfo line with something */
 void eprefix(const char * __EINFO_RESTRICT);
 
+__END_DECLS
 #endif