Subject: fix portability issues that led to Hurd build failures

* src/build-system/configure(.ac):
  - Reflect the Hurd's support for -Wl,rpath,... .
* src/connect/ncbi_socket_cxx.cpp, src/connect/ext/ncbi_localnet.c:
  cope with missing PATH_MAX everywhere, not just under Windows.

Author: Aaron M. Ucko <ucko@debian.org>
Last-Update: 2011-06-10
--- a/c++/src/build-system/configure
+++ b/c++/src/build-system/configure
@@ -5817,7 +5817,7 @@
     solaris* )
       CONF_f_runpath="-R"
       ;;
-    linux*:GCC | *bsd*:GCC | cygwin*:GCC | osf*:GCC )
+    linux*:GCC | *bsd*:GCC | cygwin*:GCC | osf*:GCC | gnu*:GCC )
       CONF_f_runpath="-Wl,-rpath,"
       ;;
     linux*:ICC )
--- a/c++/src/build-system/configure.ac
+++ b/c++/src/build-system/configure.ac
@@ -1535,7 +1535,7 @@
     solaris* )
       CONF_f_runpath="-R"
       ;;
-    linux*:GCC | *bsd*:GCC | cygwin*:GCC | osf*:GCC )
+    linux*:GCC | *bsd*:GCC | cygwin*:GCC | osf*:GCC | gnu*:GCC )
       CONF_f_runpath="-Wl,-rpath,"
       ;;
     linux*:ICC )
--- a/c++/src/connect/ncbi_socket_cxx.cpp
+++ b/c++/src/connect/ncbi_socket_cxx.cpp
@@ -35,7 +35,7 @@
 #include "ncbi_assert.h"                // no _ASSERT()s, keep clean from xncbi
 #include <connect/ncbi_socket_unix.hpp>
 #include <limits.h>                     // for PATH_MAX
-#if defined(NCBI_OS_MSWIN)  &&  !defined(PATH_MAX)
+#ifndef PATH_MAX
 #  define PATH_MAX 512                  // will actually use less than 32 chars
 #endif // NCBI_OS_MSWIN && !PATH_MAX
 
--- a/c++/src/connect/ext/ncbi_localnet.c
+++ b/c++/src/connect/ext/ncbi_localnet.c
@@ -64,6 +64,8 @@
 
 #if defined(NCBI_OS_MSWIN) && !defined(PATH_MAX)
 #  define PATH_MAX _MAX_PATH
+#elif !defined(PATH_MAX)
+#  define PATH_MAX 4096
 #endif /*NCBI_OS_MSWIN && !PATH_MAX*/
 
 #if PATH_MAX < 256
