[travis] MAKE was not a good name for an env var

this actually controls what make binary is used in autofools projects,
apparently

.travis.yml

@@ -24,7 +24,7 @@ before_install:
   - |-
     : ${OPTS:="config.opts/travis.ninja"} && export OPTS
   - |-
-    : ${MAKE:="ninja"} && export MAKE
+    : ${BUILD_CMD:="ninja"} && export BUILD_CMD
   # workaround for https://github.com/travis-ci/travis-ci/issues/5285
   - sudo sed -i 's/us-central1.gce/us-central1.gce.clouds/' /etc/apt/sources.list && sudo apt-get update
   - sudo -E apt-get install -y -q python-pip python3-pip
@@ -56,16 +56,16 @@ install:
 
 before_script:
     - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} configure
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE}
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE} -k test_binaries
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD}
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD} -k test_binaries
 
 script:
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE} test
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD} test
     - ${TRAVIS_BUILD_DIR}/scripts/upload_test_logs.bash
     - $HOME/src/scripts/python/
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE} headercheck -k
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE} install | grep -v "Installing"
-    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${MAKE} package_source
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD} headercheck -k
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD} install | grep -v "Installing"
+    - ${SRC_DCTRL} ${DCTRL_ARG} --only=${MY_MODULE} bexec ${BUILD_CMD} package_source
 
 # runs independent of 'script' failure/success
 after_script:
@@ -153,7 +153,7 @@ matrix:
           packages:
           - *commonpackages
           - ['clang-3.7']
-      env: OPTS_FILE=config.opts/travis.make MAKE="make -j2" CXX_COMPILER=clang++-3.7 COMPILER=clang-3.7
+      env: OPTS_FILE=config.opts/travis.make BUILD_CMD="make -j2" CXX_COMPILER=clang++-3.7 COMPILER=clang-3.7
 
     #- os: linux
       #compiler: clang