lang/gcc10: fix runtime on powerpc64le

It looks like this part was omitted during upstreaming.
Its lack causes gcc to be compiled successfully, but fail at building simple programs:
/usr/local/bin/ld: /usr/local/lib/gcc10/libgcc_s.so: undefined reference to `.__udivmodti4'
/usr/local/bin/ld: /usr/local/lib/gcc10/libgcc_s.so: undefined reference to `.__ctzdi2'
/usr/local/bin/ld: /usr/local/lib/gcc10/libgcc_s.so: undefined reference to `.__parityti2'
/usr/local/bin/ld: /usr/local/lib/gcc10/libgcc_s.so: undefined reference to `.__enable_execute_stack'

lang/gcc10/files/patch-gcc_configure

@@ -0,0 +1,11 @@
+--- gcc/configure.orig	2021-04-29 10:19:44 UTC
++++ gcc/configure
+@@ -29405,7 +29405,7 @@ $as_echo "#define HAVE_LD_PPC_GNU_ATTR_LONG_DOUBLE 1" 
+ esac
+ 
+ case "$target:$tm_file" in
+-  powerpc64-*-freebsd* | powerpc64*-*-linux* | powerpc*-*-linux*rs6000/biarch64.h*)
++  powerpc64*-*-freebsd* | powerpc64*-*-linux* | powerpc*-*-linux*rs6000/biarch64.h*)
+   case "$target" in
+      *le-*-linux*)
+      emul_name="-melf64lppc"