building on FreeBSD 11 with clang 3.8.8

Fails with:

/home/thomas/Downloads/kdenlive-16.08.2/src/scopes/audioscopes/spectrogram.cpp:248:81: error: call to 'abs' is ambiguous
                hideText = m_aTrackMouse->isChecked() && m_mouseWithinWidget && abs(x-(leftDist + mouseX + 20)) < (int) minDistX + 16
                                                                                ^~~
/usr/include/stdlib.h:83:6: note: candidate function
int      abs(int) __pure2;
         ^
/usr/include/c++/v1/stdlib.h:115:44: note: candidate function
inline _LIBCPP_INLINE_VISIBILITY long      abs(     long __x) _NOEXCEPT {return  labs(__x);}
                                           ^
/usr/include/c++/v1/stdlib.h:117:44: note: candidate function
inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {return llabs(__x);}
                                           ^
/usr/include/c++/v1/math.h:646:1: note: candidate function
abs(float __lcpp_x) _NOEXCEPT {return fabsf(__lcpp_x);}
^
/usr/include/c++/v1/math.h:650:1: note: candidate function
abs(double __lcpp_x) _NOEXCEPT {return fabs(__lcpp_x);}
^
/usr/include/c++/v1/math.h:654:1: note: candidate function
abs(long double __lcpp_x) _NOEXCEPT {return fabsl(__lcpp_x);}
^
/home/thomas/Downloads/kdenlive-16.08.2/src/scopes/audioscopes/spectrogram.cpp:276:77: error: call to 'abs' is ambiguous
            hideText = m_aTrackMouse->isChecked() && m_mouseWithinWidget && abs(x-(leftDist + mouseX + 30)) < (int) minDistX
                                                                            ^~~
/usr/include/stdlib.h:83:6: note: candidate function
int      abs(int) __pure2;
         ^
/usr/include/c++/v1/stdlib.h:115:44: note: candidate function
inline _LIBCPP_INLINE_VISIBILITY long      abs(     long __x) _NOEXCEPT {return  labs(__x);}
                                           ^
/usr/include/c++/v1/stdlib.h:117:44: note: candidate function
inline _LIBCPP_INLINE_VISIBILITY long long abs(long long __x) _NOEXCEPT {return llabs(__x);}
                                           ^
/usr/include/c++/v1/math.h:646:1: note: candidate function
abs(float __lcpp_x) _NOEXCEPT {return fabsf(__lcpp_x);}
^
/usr/include/c++/v1/math.h:650:1: note: candidate function
abs(double __lcpp_x) _NOEXCEPT {return fabs(__lcpp_x);}
^
/usr/include/c++/v1/math.h:654:1: note: candidate function
abs(long double __lcpp_x) _NOEXCEPT {return fabsl(__lcpp_x);}
^
2 errors generated.
--- src/CMakeFiles/kdenlive.dir/scopes/audioscopes/spectrogram.cpp.o ---
*** [src/CMakeFiles/kdenlive.dir/scopes/audioscopes/spectrogram.cpp.o] Error code 1

make[2]: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build
1 error

make[2]: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build
--- src/CMakeFiles/kdenlive.dir/all ---
*** [src/CMakeFiles/kdenlive.dir/all] Error code 2

make[1]: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build
1 error

make[1]: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build
*** [all] Error code 2

make: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build
1 error

make: stopped in /usr/home/thomas/Downloads/kdenlive-16.08.2/build