re PR libstdc++/85768 (FreeBSD bootstrap fails due to undefined reference to 'backtrace')

2018-05-25  François Dumont  <fdumont@gcc.gnu.org>

	PR libstdc++/85768
	* src/c++11/debug.cc: Remove backtrace usage.

From-SVN: r260761

libstdc++-v3/ChangeLog

+2018-05-25  François Dumont  <fdumont@gcc.gnu.org>
+
+	PR libstdc++/85768
+	* src/c++11/debug.cc: Remove backtrace usage.
+
 2018-05-24  Maya Rashish  <coypu@sdf.org>
 
 	PR target/85904

libstdc++-v3/src/c++11/debug.cc

@@ -40,7 +40,8 @@
 
 #include <cxxabi.h> // for __cxa_demangle
 
-#if defined _GLIBCXX_HAVE_EXECINFO_H
+// libstdc++/85768
+#if 0 // defined _GLIBCXX_HAVE_EXECINFO_H
 # include <execinfo.h> // for backtrace
 #endif
 
@@ -1050,7 +1051,8 @@ namespace __gnu_debug
 	print_literal(ctx, "\n");
       }
 
-#if defined _GLIBCXX_HAVE_EXECINFO_H
+// libstdc++/85768
+#if 0 //defined _GLIBCXX_HAVE_EXECINFO_H
     {
       void* stack[32];
       int nb = backtrace(stack, 32);