[committed] libstdc++: Fix syntax error in libbacktrace configuration

[Jonathan Wakely <jwakely@redhat.com>]

Tested x86_64-linux, pushed to trunk.

-- >8 --

Using == instead of = causes a configuration error with dash as the
shell:

checking whether to build libbacktrace support... /home/devel/building/work/src/gcc-12-20220417/libstdc++-v3/configure: 77471: test: auto: unexpected operator
/home/devel/building/work/src/gcc-12-20220417/libstdc++-v3/configure: 77474: test: auto: unexpected operator
auto

This means we fail to change the value from "auto" to "no" and so this
test passes:
GLIBCXX_CONDITIONAL(ENABLE_BACKTRACE, [test "$enable_libstdcxx_backtrace" != no])

This leads to the libbacktrace directory being included in the build
without being configured properly, and bootstrap fails.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (GLIBCXX_ENABLE_BACKTRACE): Fix shell operators.
	* configure: Regenerate.
---
 libstdc++-v3/acinclude.m4 | 6 +++---
 libstdc++-v3/configure    | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 6aece2adff8..138bd58d86c 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -5007,10 +5007,10 @@ esac
 BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DBACKTRACE_ELF_SIZE=$elfsize"
 
   AC_MSG_CHECKING([whether to build libbacktrace support])
-  if test "$enable_libstdcxx_backtrace" == "auto"; then
+  if test "$enable_libstdcxx_backtrace" = "auto"; then
     enable_libstdcxx_backtrace=no
   fi
-  if test "$enable_libstdcxx_backtrace" == "yes"; then
+  if test "$enable_libstdcxx_backtrace" = "yes"; then
     BACKTRACE_SUPPORTED=1
 
     AC_CHECK_HEADERS(sys/mman.h)
@@ -5057,7 +5057,7 @@ BACKTRACE_CPPFLAGS="$BACKTRACE_CPPFLAGS -DBACKTRACE_ELF_SIZE=$elfsize"
     BACKTRACE_SUPPORTS_THREADS=0
   fi
   AC_MSG_RESULT($enable_libstdcxx_backtrace)
-  GLIBCXX_CONDITIONAL(ENABLE_BACKTRACE, [test "$enable_libstdcxx_backtrace" != no])
+  GLIBCXX_CONDITIONAL(ENABLE_BACKTRACE, [test "$enable_libstdcxx_backtrace" = yes])
 ])
 
 # Macros from the top-level gcc directory.