gcj 6.5.0 cannot support ARMv8.2 - peg it to ARMv8.1

Makefile

+GCC_CONFIG := $(subst cortex-a75,cortex-a72,\
+              $(subst armv8.2-a,armv8.1-a,\
+              $(subst +fp16,,\
+              $(subst +dotprod,,\
+              $(subst skylake,broadwell,\
+              $(GCC_CONFIG))))))
+
 temporary:
 	dd if=/dev/zero of=swap bs=1048576 count=1024
 	chmod 600 swap
@@ -14,7 +21,7 @@ temporary:
 	cd gcc-6.5.0 && sed -e '/GLIBC_DYNAMIC_LINKER64/s/lib64/lib/' -i gcc/config/i386/linux64.h
 	cd gcc-6.5.0 && cp ../ecj-4.9.jar ./ecj.jar
 	mkdir gcc-build
-	cd gcc-build && ../gcc-6.5.0/configure --prefix=/build/usr --disable-multilib --with-system-zlib --enable-java-home --with-jvm-root-dir=/build/opt/gcj --enable-languages=java $(GCC_CONFIG:skylake=broadwell)
+	cd gcc-build && ../gcc-6.5.0/configure --prefix=/build/usr --disable-multilib --with-system-zlib --enable-java-home --with-jvm-root-dir=/build/opt/gcj --enable-languages=java $(GCC_CONFIG)
 	$(MAKE) -C gcc-build
 
 # FIXME: gcc tests fail, we should exclude tests which are known to fail and beyond our control