Compilation without threads does not seem to work #136

./configure --enable-static --disable-shared --disable-examples --disable-flatzinc --disable-gist --disable-qt --disable-float-vars --disable-thread --disable-doc-dot --disable-profile --disable-debug -disable-doc-tagfile

$ make
make[1]: `gecode/kernel/var-type.hpp' is up to date.
make[1]: `gecode/kernel/var-imp.hpp' is up to date.
g++ -I. -Qunused-arguments -fno-rounding-math -ffinite-math-only -fno-math-errno -fno-strict-aliasing -O3 -fvisibility=hidden -ggdb -std=c++17 -pipe -Wno-unknown-pragmas -Wall -Wextra -fPIC -DNDEBUG   \
	-c -o gecode/support/exception.o  gecode/support/exception.cpp
In file included from gecode/support/exception.cpp:34:
In file included from ./gecode/support.hh:102:
./gecode/support/thread.hpp:114:2: error: No suitable mutex implementation found
#error No suitable mutex implementation found
 ^
1 error generated.
make[1]: *** [gecode/support/exception.o] Error 1
make: *** [compilelib] Error 2