CI: Disable MinGW build on Travis and add AppVeyor badge

Now that AppVeyor handles testing Windows builds with MSVC,
we can skip the need to test against Travis' old MinGW toolchain
and have a faster CI process.

Also try building X11 binaries against system OpenSSL, should
speed up build.

.appveyor.yml

@@ -21,4 +21,4 @@ before_build:
   - cl.exe
 
 build_script:
-- scons platform=%GD_PLATFORM% target=%TARGET% tools=%TOOLS%
+- scons platform=%GD_PLATFORM% target=%TARGET% tools=%TOOLS% progress=no

.travis.yml

@@ -19,7 +19,7 @@ env:
   - GODOT_TARGET=osx
   - GODOT_TARGET=x11
   #- GODOT_TARGET=android
-  - GODOT_TARGET=windows
+  #- GODOT_TARGET=windows
 
 matrix:
   include:
@@ -66,13 +66,13 @@ addons:
       - libxrandr-dev
 
       # For cross-compiling to Windows.
-      - binutils-mingw-w64-i686
-      - binutils-mingw-w64-x86-64
-      - gcc-mingw-w64-i686
-      - gcc-mingw-w64-x86-64
-      - g++-mingw-w64-i686
-      - g++-mingw-w64-x86-64
-      - mingw-w64
+      #- binutils-mingw-w64-i686
+      #- binutils-mingw-w64-x86-64
+      #- gcc-mingw-w64-i686
+      #- gcc-mingw-w64-x86-64
+      #- g++-mingw-w64-i686
+      #- g++-mingw-w64-x86-64
+      #- mingw-w64
 
       # For style checks.
       - clang-format-3.9
@@ -92,5 +92,5 @@ script:
   - if [ "$STATIC_CHECKS" = "yes" ]; then
       sh ./misc/travis/clang-format.sh;
     else
-      scons -j 2 platform=$GODOT_TARGET progress=no verbose=yes CXX=$CXX builtin_openssl=yes;
+      scons -j 2 platform=$GODOT_TARGET progress=no verbose=yes CXX=$CXX;
     fi

README.md

@@ -62,5 +62,6 @@ There are also a number of other learning resources provided by the community,
 such as text and video tutorials, demos, etc. Consult the [community channels](https://godotengine.org/community)
 for more info.
 
-[![Build Status](https://travis-ci.org/godotengine/godot.svg?branch=master)](https://travis-ci.org/godotengine/godot)
+[![Travis Build Status](https://travis-ci.org/godotengine/godot.svg?branch=master)](https://travis-ci.org/godotengine/godot)
+[![AppVeyor Build Status](https://ci.appveyor.com/api/projects/status/bfiihqq6byxsjxxh/branch/master?svg=true)](https://ci.appveyor.com/project/akien-mga/godot)
 [![Code Triagers Badge](https://www.codetriage.com/godotengine/godot/badges/users.svg)](https://www.codetriage.com/godotengine/godot)