Enable multiarch support in pass-1 GCC.

By default, it is 'auto' - which means, it is enabled if there are
multilibs directories detected in the installation location for libgcc.
Thus, it is not detected for pass-1 GCC: the installation location is
empty at this point.

Signed-off-by: Alexey Neyman <stilor@att.net>

scripts/build/cc/100-gcc.sh

@@ -403,10 +403,17 @@ do_gcc_core_backend() {
         extra_config+=("--with-system-zlib")
     fi
 
-    # Some versions of gcc have a deffective --enable-multilib.
-    # Since that's the default, only pass --disable-multilib.
+    # Some versions of gcc have a defective --enable-multilib.
+    # Since that's the default, only pass --disable-multilib. For multilib,
+    # also enable multiarch. Without explicit --enable-multiarch, pass-1
+    # compiler is configured as multilib/no-multiarch and pass-2/final
+    # are multilib/multiarch (because gcc autodetects multiarch based on
+    # multiple instances of crt*.o in the install directory - which do
+    # not exist in pass-1).
     if [ "${CT_MULTILIB}" != "y" ]; then
         extra_config+=("--disable-multilib")
+    else
+        extra_config+=("--enable-multiarch")
     fi
 
     CT_DoLog DEBUG "Extra config passed: '${extra_config[*]}'"
@@ -880,10 +887,12 @@ do_gcc_backend() {
         extra_config+=("--with-system-zlib")
     fi
 
-    # Some versions of gcc have a deffective --enable-multilib.
+    # Some versions of gcc have a defective --enable-multilib.
     # Since that's the default, only pass --disable-multilib.
     if [ "${CT_MULTILIB}" != "y" ]; then
         extra_config+=("--disable-multilib")
+    else
+        extra_config+=("--enable-multiarch")
     fi
 
     CT_DoLog DEBUG "Extra config passed: '${extra_config[*]}'"