Enhance Travis CI build coverage

[jeking3]

Ick...

test/ptr_set.cpp: In function ‘void test_set()’:
test/ptr_set.cpp:104: error: ‘nullptr’ was not declared in this scope
    "g++-4.4"   -std=c++0x -fvisibility-inlines-hidden -fPIC -m64 -O3 -finline-functions -Wno-inline -Wall -fvisibility=hidden  -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_STATIC_LINK=1 -DBOOST_CHRONO_THREAD_DISABLED -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_TEST_NO_AUTO_LINK=1 -DBOOST_TIMER_STATIC_LINK=1 -DNDEBUG  -I"../.." -c -o "../../bin.v2/libs/ptr_container/test/ptr_set.test/gcc-4.4/release/cxxstd-0x-iso/visibility-hidden/ptr_set.o" "test/ptr_set.cpp"
...failed gcc.compile.c++ ../../bin.v2/libs/ptr_container/test/ptr_set.test/gcc-4.4/release/cxxstd-0x-iso/visibility-hidden/ptr_set.o...

[codecov[bot]]

Codecov Report

Merging #21 into develop will increase coverage by 0.03%. The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop      #21      +/-   ##
===========================================
+ Coverage    61.24%   61.28%   +0.03%     
===========================================
  Files           35       35              
  Lines         1463     1467       +4     
  Branches       545      546       +1     
===========================================
+ Hits           896      899       +3     
  Misses          35       35              
- Partials       532      533       +1

Impacted Files	Coverage Δ
.../ptr_container/detail/reversible_ptr_container.hpp	58.95% <0%> (-0.58%)	:arrow_down:
...e/boost/ptr_container/detail/void_ptr_iterator.hpp	84% <0%> (+1.39%)	:arrow_up:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 67915a7...b358897. Read the comment docs.