Ok, I switched to Linux (GNU/Linux debian 8.1 jessie to be exact), since it seems it's not possible to compile the cross ecl on MacOSX.
But despite having a cross gcc correctly installed, when compiling the cross ecl, some libtool script cannot find it:
libtool: compile: arm-linux-androideabi-gcc -fPIC -DHAVE_CONFIG_H -I../src -I/home/pjb/src/android/ecl/src/bdwgc/libatomic_ops/src -fPIC -Wall -Wextra -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -DANDROID -DPLATFORM_ANDROID -DUSE_GET_STACKBASE_FOR_MAIN -DIGNORE_DYNAMIC_LOADING -DAO_REQUIRE_CAS -g -O2 -fPIC -D_THREAD_SAFE -MT atomic_ops.lo -MD -MP -MF .deps/atomic_ops.Tpo -c /home/pjb/src/android/ecl/src/bdwgc/libatomic_ops/src/atomic_ops.c -fPIC -DPIC -o atomic_ops.o ../libtool: line 1749: arm-linux-androideabi-gcc: command not found Makefile:597: recipe for target 'atomic_ops.lo' failed
See the end of log.txt in the attached archive.