Bug#942113: 3depict: FTBFS on PPC64EL - POWERPC macro not always defined

[Thierry Fauck@linux.ibm.com]

Changing on file side is not enough as there a couple of file impacted
  > g++ -DHAVE_CONFIG_H -I. -I..   -Wdate-time -D_FORTIFY_SOURCE=2 
-I/usr/include/freetype2 -I/usr/include/libpng16 -g -O2 
-fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat 
-Werror=format-security --std=gnu++11 
-I/usr/lib/powerpc64le-linux-gnu/wx/include/gtk3-unicode-3.0 
-I/usr/include/wx-3.0 -D_FILE_OFFSET_BITS=64 -DWXUSINGDLL -D__WXGTK__ 
-I/usr/include  -I/usr/include/libxml2 -L/lib -fopenmp 
-D_GLIBCXX_PARALLEL  -pipe  -g -O2 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. 
-fstack-protector-strong -Wformat -Werror=format-security --std=gnu++11 
-c -o backend/filters/algorithms/3Depict-spatial.o `test -f 
'backend/filters/algorithms/spatial.cpp' || echo 
'./'`backend/filters/algorithms/spatial.cpp
> In file included from /usr/include/qhull/qhull_a.h:28,
>                  from backend/filters/algorithms/spatial.cpp:30:
> /usr/include/qhull/libqhull.h:46:30: error: operator '&&' has no right operand
>    46 | #if __MWERKS__ && __POWERPC__
>       |                              ^


and included files are not common !