[C] Github. Travis CI build failing.

Hello, I recently tried configuring travis CI with my GitHub project STMP

Suffice to say, this is what happens in travis CI:

libstmp_process.a(stmp_process.c.o): In function `process_source':
/home/travis/build/ParadoxZero/stmp/stmp/src/stmp_process.c:(.text+0x357): undefined reference to `get_all_lines'
/home/travis/build/ParadoxZero/stmp/stmp/src/stmp_process.c:(.text+0x45d): undefined reference to `get_all_words'
libstmp_process.a(stmp_process.c.o): In function `parse_macro_definitions':
/home/travis/build/ParadoxZero/stmp/stmp/src/stmp_process.c:(.text+0x8e4): undefined reference to `get_all_words'
/home/travis/build/ParadoxZero/stmp/stmp/src/stmp_process.c:(.text+0xb0f): undefined reference to `get_all_words'
libstmp_process.a(stmp_process.c.o): In function `expand_macro':
/home/travis/build/ParadoxZero/stmp/stmp/src/stmp_process.c:(.text+0xdfc): undefined reference to `get_all_words'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [stmp/src/stmp] Error 1
make[1]: *** [stmp/src/CMakeFiles/stmp.dir/all] Error 2
make: *** [all] Error 

Travis yml file

sudo: required
dist: trusty

addons:
  apt:
    sources:
    # add PPAs with more up-to-date toolchains
    - ubuntu-toolchain-r-test
    - llvm-toolchain-precise-3.6
    packages:
    # install toolchains
    - gcc-5
    - g++-5
    - clang-3.6

language: c

compiler:
  - gcc
  - clang

before_script:
  - mkdir build
  - cd build
  - cmake ..

script: make 

Any idea what's causing it? The build works absolutely fine in my machine.

Please let me know what all info is needed for a hypothesis.