libstdc++: Default to C++20 in src/experimental/Makefile.am

r16-7089-gfbde291af66e02 had a stray change to the Makefile.in but
actually we probably should change that directory to use C++20, now that
it's the default. So this updates the Makefile.am, and the Makefile.in
doesn't need to be regenerated now.

libstdc++-v3/ChangeLog:

	* src/experimental/Makefile.am: Change AM_CXXFLAGS to use C++20
	by default.

diff --git a/libstdc++-v3/src/experimental/Makefile.am b/libstdc++-v3/src/experimental/Makefile.am
index e428aef23c041ae510c14fe2bea0713bbdd03580..bad10b40e21d4e7836dd8f5ca5f42f902f9364e9 100644 (file)
--- a/libstdc++-v3/src/experimental/Makefile.am
+++ b/libstdc++-v3/src/experimental/Makefile.am
@@ -67,7 +67,7 @@ libstdc__exp_la_DEPENDENCIES = \
 # OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
 # as the occasion calls for it.
 AM_CXXFLAGS = \
-       -std=gnu++17 -nostdinc++ \
+       -std=gnu++20 -nostdinc++ \
        $(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
        $(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
        $(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \