revert to macos-11, fix windows bash syntax

Author: mattip

.github/workflows/build.yml

@@ -54,9 +54,8 @@ jobs:
 
       - run: |
           # see https://www.mail-archive.com/gcc-bugs@gcc.gnu.org/msg586184.html
-          if [ "${{ matrix.BUILD_BITS }}" == "64" ]; then
+          if [ "${{ matrix.BUILD_BITS }}" != "64" ];
             # latest mingw64 is using gcc11
-          else
             include=/c/ProgramData/Chocolatey/lib/mingw/tools/install/mingw32/lib/gcc/i686-w64-mingw32/8.1.0/include/avx512fintrin.h
             sed -i -e"s/_mm512_abs_pd (__m512 __A)/_mm512_abs_pd (__m512d __A)/" $include
           fi

.github/workflows/multibuild.yml

@@ -15,17 +15,17 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-11]
         platform: [x64]
         PLAT: [i686, x86_64]
         INTERFACE64: ['', '1']
         MB_ML_VER: ['', 2010, 2014]
         include:
-          - os: macos-latest
+          - os: macos-11
             PLAT: arm64
             INTERFACE64: '1'
             platform: [x64]
-          - os: macos-latest
+          - os: macos-11
             PLAT: arm64
             INTERFACE64: ''
             platform: [x64]
@@ -42,11 +42,11 @@ jobs:
             MB_ML_VER: _1_1
             platform: [x64]
         exclude:
-          - os: macos-latest
+          - os: macos-11
             PLAT: i686
-          - os: macos-latest
+          - os: macos-11
             MB_ML_VER: 2010
-          - os: macos-latest
+          - os: macos-11
             MB_ML_VER: 2014
           - PLAT: i686
             INTERFACE64: '1'