travis: switch to ubuntu trusty

ubuntu trusty has updated doxygen 1.8.4 which is the same
stable version 1.8 which is described in DEPENDANCIES file.
Now doxygen do not generate any warnings. Compiler version
stays the same 4.8 for gcc.

Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>
Reviewed-by: Mike Holmes <mike.holmes@linaro.org>

.travis.yml

@@ -9,6 +9,7 @@
 
 language: c
 sudo: required
+dist: trusty
 env:
   global:
     # COVERITY_SCAN_TOKEN
@@ -34,13 +35,13 @@ env:
 
 matrix:
   include:
-    - compiler: gcc-4.8
+    - compiler: gcc
       addons:
         apt:
           sources:
             - ubuntu-toolchain-r-test
           packages:
-            - gcc-4.8
+            - gcc
       env: MY_CF="-O0 -coverage" MY_LDF="--coverage" DOCOV=1
     - compiler: clang
       addons:
@@ -61,6 +62,7 @@ before_install:
         - PATH=${PATH//:\.\/node_modules\/\.bin/}
 
 #       Install cunit for the validation tests because distro version is too old and fails C99 compile
+        - sudo apt-get remove libcunit1-dev libcunit1
         - export CUNIT_VERSION=2.1-3
         - curl -sSOL https://github.com/Linaro/libcunit/releases/download/${CUNIT_VERSION}/CUnit-${CUNIT_VERSION}.tar.bz2
         - tar -jxf *.bz2
@@ -124,7 +126,7 @@ script:
         - sudo rm -rf $KSRC
 
 after_success:
-  - if [ -n "$DOCOV" ]; then find . -type f -iname '*.[ch]' -not -path ".git/*" -execdir gcov-4.8 {} \; ; bash <(curl -s https://codecov.io/bash) -X coveragepy; fi
+  - if [ -n "$DOCOV" ]; then find . -type f -iname '*.[ch]' -not -path ".git/*" -execdir gcov {} \; ; bash <(curl -s https://codecov.io/bash) -X coveragepy; fi
 
 addons:
     coverity_scan: