[PATCH] Define GNULIB_NAMESPACE in unittests/string_view-selftests.c

[Simon Marchi <simon.marchi@ericsson.com>]

When building with x86_64-w64-mingw32-g++ (to test cross-compiling for
Windows), I get this error:

unittests/string_view-selftests.o: In function `selftests::string_view::inserters_2::test05(unsigned long long)':
/home/emaisin/src/binutils-gdb/gdb/unittests/basic_string_view/inserters/char/2.cc:60: undefined reference to `std::basic_ofstream<char, std::char_traits<char> >::rpl_close()'

This is caused by gnulib redefining "close" as "rpl_close", and
therefore messing up the declaration of basic_ofstream in the libstdc++
header.  The solution would be to use gnulib namespaces [1].  Until we
use them across GDB, we can use them locally in files that are
problematic, like this one.

gdb/ChangeLog:

	* unittests/string_view-selftests.c: Define GNULIB_NAMESPACE.
---
 gdb/unittests/string_view-selftests.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gdb/unittests/string_view-selftests.c b/gdb/unittests/string_view-selftests.c
index 182a5df..55ffe64 100644
--- a/gdb/unittests/string_view-selftests.c
+++ b/gdb/unittests/string_view-selftests.c
@@ -21,6 +21,8 @@
    the "real" version.  */
 #if __cplusplus < 201703L
 
+#define GNULIB_NAMESPACE gnulib
+
 #include "defs.h"
 #include "selftest.h"
 #include "common/gdb_string_view.h"
-- 
2.7.4