toolchain: introduce BR2_TOOLCHAIN_HAS_GCC_BUG_90620

GCC fails building the haproxy package for the Microblaze architecture:

  http://autobuild.buildroot.org/results/64706f96db793777de9d3ec63b0a47d776cf33fd/

The gcc bug was originally reported gpsd:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90620

This gcc bug no longer appeared with gcc 8.x but reappeared in gcc
9.x, so we introduce a config symbol so that packages can work it
around by disabling optimization.

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

toolchain/Config.in

@@ -145,6 +145,14 @@ config BR2_TOOLCHAIN_HAS_GCC_BUG_85862
 	default y if BR2_microblaze
 	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_7
 
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90620
+# ICE: in do_output_reload, at reload1.c:7978 on microblaze.
+# It's been fixed on Gcc 8.x but reappeared on Gcc 9.x
+config BR2_TOOLCHAIN_HAS_GCC_BUG_90620
+	bool
+	default y if BR2_microblaze
+	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_8 || BR2_TOOLCHAIN_GCC_AT_LEAST_9
+
 config BR2_TOOLCHAIN_HAS_NATIVE_RPC
 	bool