.travis.yml: Simplify, remove esp-open-rtos specific things.

Before picking esp-open-rtos', I tried to add corresponding steps to
standard MicroPython's .travis.yml, but it just doesn't work in that
configuration (sudo: yes is the biggest difference), with completely
senseless errors popping up, and working them around turns into very
time consuming firefighting.

.travis.yml

@@ -1,54 +1,50 @@
-sudo: required
-dist: trusty
 language: c
-compiler:
-  - gcc
+sudo: false
+env:
+  # Target commit for https://github.com/pfalcon/esp-open-sdk/
+  CROSS_ROOT="${HOME}/toolchain-xtensa"
+  CROSS_BINDIR="${CROSS_ROOT}/bin"
+  PATH=${PATH}:${CROSS_BINDIR}
+cache:
+  directories:
+    - ${CROSS_ROOT}
+addons:
+  apt:
+    packages:
+    - make
+    - unrar
+    - autoconf
+    - automake
+    - libtool
+    - gcc
+    - g++
+    - gperf
+    - flex
+    - bison
+    - texinfo
+    - gawk
+    - libncurses5-dev
+    - libexpat1-dev
+    - python
+    - python-serial
+    - sed
+    - git
+    - help2man
 
-before_script:
-# Extra CPython versions
-#  - sudo add-apt-repository -y ppa:fkrull/deadsnakes
-# Extra gcc versions
-#  - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
-  - sudo add-apt-repository -y ppa:terry.guo/gcc-arm-embedded
-  - sudo dpkg --add-architecture i386
-  - sudo apt-get update -qq || true
-  - sudo apt-get install -y python3 gcc-multilib pkg-config libffi-dev libffi-dev:i386 qemu-system mingw32
-  - sudo apt-get install -y --force-yes gcc-arm-none-eabi
-  # For teensy build
-  - sudo apt-get install realpath
-  # For coverage testing
-  - sudo pip install cpp-coveralls
-  - gcc --version
-  - arm-none-eabi-gcc --version
-  - python3 --version
+before_install:
+  # Install a toolchain using esp-open-sdk (parts we need for this are the GNU toolchain and libhal)
+  #
+  # Adds hack of "{$HAS_TC} || -Buildstep-" to avoid rebuilding toolchain if it's already
+  # installed from the cache. If this gets any more complex it should be spun out to a standalone shell script.
+  - export HAS_TC="test -d ${CROSS_BINDIR}"
+  - unset CC # Travis sets this due to "language: c", but it confuses autotools configure when cross-building
+  - ${HAS_TC} || git clone --recursive https://github.com/pfalcon/esp-open-sdk.git
+  - ${HAS_TC} || cd esp-open-sdk
+  - ${HAS_TC} || sed -i "s/2.69/2.68/" lx106-hal/configure.ac # this is a nasty hack as Ubuntu Precise only has autoconf 2.68 not 2.69...
+  - ${HAS_TC} || sed -r -i 's%TOOLCHAIN ?=.*%TOOLCHAIN=${CROSS_ROOT}%' Makefile
+  - ${HAS_TC} || make
 
 script:
-  - make -C minimal test
-  - make -C unix deplibs
-  - make -C unix
-  - make -C unix nanbox
-  - make -C bare-arm
-  - make -C qemu-arm test
-  - make -C stmhal
-  - make -C stmhal -B MICROPY_PY_WIZNET5K=1 MICROPY_PY_CC3K=1
-  - make -C stmhal BOARD=STM32F4DISC
-  - make -C teensy
-  - make -C cc3200 BTARGET=application BTYPE=release
-  - make -C cc3200 BTARGET=bootloader  BTYPE=release
-  - make -C windows CROSS_COMPILE=i586-mingw32msvc-
-
-  # run tests without coverage info
-  #- (cd tests && MICROPY_CPYTHON3=python3.4 ./run-tests)
-  #- (cd tests && MICROPY_CPYTHON3=python3.4 ./run-tests --emit native)
-
-  # run tests with coverage info
-  - make -C unix coverage
-  - (cd tests && MICROPY_CPYTHON3=python3.4 MICROPY_MICROPYTHON=../unix/micropython_coverage ./run-tests)
-  - (cd tests && MICROPY_CPYTHON3=python3.4 MICROPY_MICROPYTHON=../unix/micropython_coverage ./run-tests --emit native)
-
-after_success:
-  - (cd unix && coveralls --root .. --build-root . --gcov $(which gcov) --gcov-options '\-o build-coverage/' --include py --include extmod)
-
-after_failure:
-  - (cd tests && for exp in *.exp; do testbase=$(basename $exp .exp); echo -e "\nFAILURE $testbase"; diff -u $testbase.exp $testbase.out; done)
-  - (grep "FAIL" qemu-arm/build/console.out)
+  - cd ${TRAVIS_BUILD_DIR}
+  - make -C esp8266 axtls
+  - make -C esp8266