Minor: clinker/libffi: cast to pointer from integer & comparison between pointer and integer

[dumblob]

...
cd libffi && make -f Makefile
make[4]: Entering directory '/home/test/dao/modules/clinker/libffi'
cc -ggdb -O0 -DDEBUG -fPIC -fPIC -Iinclude/ -Isrc/x86/  -c src/closures.c -o DaoMake.Objs/closures.c.54E4.o
cc -ggdb -O0 -DDEBUG -fPIC -fPIC -Iinclude/ -Isrc/x86/  -c src/dlmalloc.c -o DaoMake.Objs/dlmalloc.c.5B52.o
src/dlmalloc.c: In function ‘mmap_resize’:
src/dlmalloc.c:3255:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
     char* cp = (char*)CALL_MREMAP((char*)oldp - offset,
                ^
src/dlmalloc.c: In function ‘sys_trim’:
src/dlmalloc.c:3674:62: warning: comparison between pointer and integer
             if ((CALL_MREMAP(sp->base, sp->size, newsize, 0) != MFAIL) ||
                                                              ^
...