travisci: Adjust build config to use "make all" on Linux

For Linux build testing, we want all targets compiled. To do so
without a cross-toolchain, simply use the host compiler for the
target tools. This can be achieved by setting CROSS_COMPILE to
an empty string.

OSX can't handle this: It neither supports "-static", nor would
it successfully compile meminfo.c. Thus we keep the default
"make", which should only build the 'tools' target.

On Linux we'll also test the install-* targets by requesting
installation to /tmp/sunxi-tools as a post-build step.
Signed-off-by: Bernhard Nortmann <bernhard.nortmann@web.de>

.travis.yml

@@ -3,6 +3,9 @@ sudo: false
 
 language: c
 
+# treat all warnings as errors
+env: EXTRA_CFLAGS=-Werror
+
 os:
   - linux
   - osx
@@ -10,7 +13,7 @@ compiler:
   - gcc
   - clang
 
-# OSX uses Apple's flavor of clang anyway, so there's no point in using "gcc".
+# OSX uses Apple's flavor of clang anyway, so there's no point in trying "gcc".
 # This excludes the "gcc" compiler from the build matrix for OSX:
 matrix:
   exclude:
@@ -23,17 +26,24 @@ addons:
     packages:
     - libusb-1.0-0-dev
 
-# take care of the libusb dependency for Mac OS X
+# take care of the libusb dependency for Mac OS X; on Linux use "make all" later
 before_install:
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
       brew update;
       brew install libusb;
+    else
+      export TARGET="all CROSS_COMPILE=";
     fi
 
-# build using the Makefile, treat all warnings as errors
+# build using the Makefile
 script:
-  - make EXTRA_CFLAGS=-Werror
-  - make misc EXTRA_CFLAGS=-Werror
+  - make ${TARGET} && make misc
+
+# when on Linux: run/simulate a test install
+after_success:
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
+      make install-all install-misc DESTDIR=/tmp PREFIX=/sunxi-tools;
+    fi
 
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