modules : Make sure we include <map> in system.h.

It appears that many targets include the map header transitively in
other std headers included from system.h.  However there are some
editions of clang/libc++ in Xcode that do not, which results in a
bootstrap fail - since when resolver.h is included  there is then a
conflict in declaring abort().

The fix is to ensure that map is pulled in by system.h and before
resolver.h is included.  As a precautionary measure and to alert
anyone perhaps adding another header to resolver.h this patch also
gates the direct includes there on !IN_GCC.

c++tools/ChangeLog:

	* resolver.h: Do not include std headers directly when
	building in GCC.

gcc/cp/ChangeLog:

	* mapper-client.cc (INCLUDE_MAP): New; require map to be
	included from system.h.
	* mapper-resolver.cc (INCLUDE_MAP): Likewise.

c++tools/resolver.h

@@ -24,8 +24,10 @@ along with GCC; see the file COPYING3.  If not see
 // Mapper interface for client and server bits
 #include "cody.hh"
 // C++
+#if !IN_GCC
 #include <string>
 #include <map>
+#endif
 
 // This is a GCC class, so GCC coding conventions on new bits.  
 class module_resolver : public Cody::Resolver

gcc/cp/mapper-client.cc

@@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.  If not see
 #endif
 #define INCLUDE_STRING
 #define INCLUDE_VECTOR
+#define INCLUDE_MAP
 #include "system.h"
 
 #include "line-map.h"

gcc/cp/mapper-resolver.cc

@@ -24,6 +24,7 @@ along with GCC; see the file COPYING3.  If not see
 #define INCLUDE_STRING
 #define INCLUDE_VECTOR
 #define INCLUDE_ALGORITHM
+#define INCLUDE_MAP
 #include "system.h"
 
 // We don't want or need to be aware of networking