CI: Add miltilibbed Elf32 & glibc configs for ARC

As of today baremetal (AKA "Elf32") & Linux glibc toolchains are even
more important than Linux uClibc one for ARC, so adding them.

We exclude ARC Linux toolchains from Mac buils as it seem to not make
much sense and anyway glibc build for ARC700 fails,
see https://github.com/crosstool-ng/crosstool-ng/pull/1456#issuecomment-779150246

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

.github/workflows/continuous-integration-workflow.yml

@@ -60,6 +60,8 @@ jobs:
         ]
         sample: [
           "aarch64-unknown-linux-gnu",
+          "arc-multilib-elf32",
+          "arc-multilib-linux-gnu",
           "arc-multilib-linux-uclibc",
           "arm-picolibc-eabi",
           "arm-unknown-linux-gnueabi",
@@ -78,11 +80,17 @@ jobs:
           "xtensa-fsf-linux-uclibc"
         ]
         exclude:
+          # Exclude both glibc & uClibc ARC Linux toolchains as
+          # there's no known use of ARC Linux toolchains on Mac,
+          # and anyway glibc fails to build for ARC700,
+          # see https://github.com/crosstool-ng/crosstool-ng/pull/1456#issuecomment-779150246
+          - {host: "macos-10.15", sample: "arc-multilib-linux-gnu"}
+          - {host: "macos-10.15", sample: "arc-multilib-linux-uclibc"}
+
           # Exclude mips64-*-linux-gnu because of <byteswap.h> usage in
           # elf-entry.c for linux kernel headers.  <byteswap.h> is a GNU
           # extension and doesn't exist on MacOS X
-          - host: "macos-10.15"
-            sample: "mips64-unknown-linux-gnu"
+          - {host: "macos-10.15", sample: "mips64-unknown-linux-gnu"}
     steps:
       - name: Create case sensitive workspace volume for macOS
         if: ${{ runner.os == 'macOS' }}