[CI] Support mingw in 32 bits

.ci/scripts/install-tools.bat

@@ -1,6 +1,13 @@
 set GOPATH=%WORKSPACE%
 set MAGEFILE_CACHE=%WORKSPACE%\.magefile
-set PATH=%WORKSPACE%\bin;C:\ProgramData\chocolatey\bin;C:\tools\mingw64\bin;%PATH%
+set PATH=%WORKSPACE%\bin;C:\ProgramData\chocolatey\bin;%PATH%
+
+REM Configure GCC for either 32 or 64 bits
+IF EXIST "%PROGRAMFILES(X86)%" (
+    set PATH=C:\tools\mingw64\bin;%PATH%
+) ELSE (
+    set PATH=C:\tools\mingw32\bin;%PATH%
+)
 
 where /q curl
 IF ERRORLEVEL 1 (
@@ -28,14 +35,15 @@ go get github.com/magefile/mage
 mage -version
 where mage
 
-if not exist C:\Python38\python.exe (
+IF not exist C:\Python38\python.exe (
     REM Install python 3.8.
     choco install python -y -r --no-progress --version 3.8.2 || echo ERROR && exit /b
 )
 python --version
 where python
 
-if not exist C:\tools\mingw64\bin\gcc.exe (
+where /q gcc
+IF ERRORLEVEL 1 (
     REM Install mingw 5.3.0
     choco install mingw -y -r --no-progress --version 5.3.0 || echo ERROR && exit /b
 )

.ci/windows.groovy

@@ -419,14 +419,16 @@ def withBeatsEnvWin(Closure body) {
   // NOTE: to support Windows 7 32 bits the arch in the go context path is required.
   def arch = is32bit() ? '386' : 'amd64'
   def goRoot = "${env.USERPROFILE}\\.gvm\\versions\\go${GO_VERSION}.windows.${arch}"
+  // NOTE: to support Windows 7 32 bits the arch in the mingw context path is required.
+  def mingwArch =  is32bit() ? '32' : '64'
 
   withEnv([
     "HOME=${env.WORKSPACE}",
     "DEV_ARCH=${arch}",
     "DEV_OS=windows",
     "GOPATH=${env.WORKSPACE}",
     "GOROOT=${goRoot}",
-    "PATH=${env.WORKSPACE}\\bin;${goRoot}\\bin;${chocoPath};${chocoPython3Path};C:\\tools\\mingw64\\bin;${env.PATH}",
+    "PATH=${env.WORKSPACE}\\bin;${goRoot}\\bin;${chocoPath};${chocoPython3Path};C:\\tools\\mingw${mingwArch}\\bin;${env.PATH}",
     "MAGEFILE_CACHE=${env.WORKSPACE}\\.magefile",
     "TEST_COVERAGE=true",
     "RACE_DETECTOR=true",