Travis: split build by target instead of vehicle

This way we can group together the builds that are fast so we pay the
"setup price" just once.  Let the long PX4 build on its own VM because
it's the one that takes most of the time building NuttX.

By grouping the projects by target it's also easier to split the build
in more VMs if we want to speed up the build.

.travis.yml

@@ -21,11 +21,8 @@ env:
     #   via the "travis encrypt" command using the project repo's public key
     - secure: "FjIwqZQV2FhNPWYITX5LZXTE38yYqBaQdbm3QmbEg/30wnPTm1ZOLIU7o/aSvX615ImR8kHoryvFPDQDWc6wWfqTEs3Ytq2kIvcIJS2Y5l/0PFfpWJoH5gRd6hDThnoi+1oVMLvj1+bhn4yFlCCQ2vT/jxoGfiQqqgvHtv4fLzI="
   matrix:
-    - TRAVIS_BUILD_TYPE=ArduPlane
-    - TRAVIS_BUILD_TYPE=ArduCopter
-    - TRAVIS_BUILD_TYPE=APMrover2
-    - TRAVIS_BUILD_TYPE=AntennaTracker
-    - TRAVIS_BUILD_TYPE=Tools/Replay
+    - TRAVIS_BUILD_TARGET="px4-v2"
+    - TRAVIS_BUILD_TARGET="sitl linux apm2 navio"
 
 addons:
   coverity_scan:

Tools/scripts/build_all_travis.sh

@@ -10,12 +10,10 @@ set -x
 
 . ~/.profile
 
-travis_build_type_or_empty() {
-    if [ -z "$TRAVIS_BUILD_TYPE" ] || [ "$TRAVIS_BUILD_TYPE" = "$1" ]; then
-        return 0
-    fi
-    return 1
-}
+# If TRAVIS_BUILD_TARGET is not set, default to all of them
+if [ -z "$TRAVIS_BUILD_TARGET" ]; then
+    TRAVIS_BUILD_TARGET="sitl linux apm2 navio px4-v2"
+fi
 
 declare -A build_platforms
 declare -A build_concurrency
@@ -35,19 +33,21 @@ build_concurrency=(["apm2"]="-j2"
 
 build_extra_clean=(["px4-v2"]="make px4-cleandep")
 
-for d in "${!build_platforms[@]}"; do
-    if ! travis_build_type_or_empty "$d"; then
+echo "Targets: $TRAVIS_BUILD_TARGET"
+for t in $TRAVIS_BUILD_TARGET; do
+    for v in ${!build_platforms[@]}; do
+        if [[ ${build_platforms[$v]} != *$t* ]]; then
             continue
         fi
+        echo "Building $v for ${t}..."
 
-    pushd $d
-    for p in ${build_platforms["$d"]}; do
+        pushd $v
         make clean
-        if [ ${build_extra_clean[$p]+_} ]; then
-            ${build_extra_clean[$p]}
+        if [ ${build_extra_clean[$t]+_} ]; then
+            ${build_extra_clean[$t]}
         fi
 
-        make $p ${build_concurrency[$p]}
-    done
+        make $t ${build_concurrency[$t]}
         popd
+    done
 done