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.