attempt to get all 3.7.0 builds working in travis successfully

multiple flavours of unix including bionic and xenial
multiple Windows builds including visual studio and mingw
msdos cross-compile on unix

.travis.yml

@@ -5,6 +5,11 @@ matrix:
       env: DESCR=linux-xenial-gcc HINTS=linux
       compiler: gcc
       script: "cd sys/unix/ && sh setup.sh hints/$HINTS && cd ../../ && make fetch-lua && make install"
+    - os: linux
+      env: DESCR=linux-bionic-gcc HINTS=linux
+      dist: bionic
+      compiler: gcc
+      script: "cd sys/unix/ && sh setup.sh hints/$HINTS && cd ../../ && make fetch-lua && make install"
     - os: linux
       env: DESCR=linux-xenial-clang HINTS=linux
       compiler: clang
@@ -74,6 +79,17 @@ matrix:
       language: shell
       script:
         - ./win/win32/vs2017/travisci.sh
+    - os: windows
+#     install: choco install mingw
+      env: DESCR=windows-mingw
+      script:
+        - sh sys/winnt/travis-gcc.sh
+        - export ADD_CURSES=Y
+        - export PDCURSES_TOP=../lib/pdcurses
+        - export LUA_VERSION=5.3.5
+        - cd src
+        - cp ../sys/winnt/Makefile.gcc ./Makefile
+        - mingw32-make install
     - os: linux
       env: DESCR=msdos-cross-on-linux HINTS=linux LUA_VERSION=5.3.5
       compiler: gcc
@@ -84,16 +100,6 @@ matrix:
         - cd lib/lua-$LUA_VERSION/src && make a && cd ../../.. 
         - sh sys/msdos/msdos-cross-compile.sh
   exclude:
-    - os: windows
-#     install: choco install mingw
-      env: DESCR=windows-mingw
-      script:
-        - git clone --depth 1 https://github.com/wmcbrine/PDCurses.git ../pdcurses
-        - export ADD_CURSES=Y
-        - export PDCURSES_TOP=../../pdcurses
-        - cd src
-        - cp ../sys/winnt/Makefile.gcc ./Makefile
-        - mingw32-make install
 #    - os: osx
 #      osx_image: xcode10.3
 #      env: DESCR=osx-xcode10.3-x11 HINTS=macosx10.14 WANT_WIN_CURSES=1 WANT_WIN_X11=1 USE_XPM=1