toolchain/toolchain-external/toolchain-external-bootlin: drop Microblaze/bleeding-edge

GCC 14.x has a significant bug where libatomic lacks some important
functions, causing the toolchain to be pretty much
unusable. Therefore, let's drop this toolchain entirely from our
listing for now.

See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118280 for more
details.

Fixes:

  http://autobuild.buildroot.net/results/dd081ca3c5746b980b0bcdf1f12b1a26c6b7ef86/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>

support/scripts/gen-bootlin-toolchains

@@ -478,6 +478,12 @@ def get_toolchains():
             elif parts[2].startswith("bleeding-edge-"):
                 variant = "bleeding-edge"
                 version = parts[2][len("bleeding-edge-"):]
+
+            # GCC 14.x on Microblaze is very broken, see
+            # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118280
+            if arch in ["microblazeel", "microblazebe"] and variant == "bleeding-edge":
+                continue
+
             tmp[(arch, libc, variant)] = version
 
         if len(tmp) == 0: