libx86: Add patch from debian to fix build on ARM

Without this, the build fails even with x86emu:

make LIBRARY=static static
make[1]: Entering directory '/tmp/nix-build-libx86-1.1.drv-0/libx86-1.1'
gcc -O2 -Wall -DDEBUG -g   -c -o x86-common.o x86-common.c
gcc -O2 -Wall -DDEBUG -g   -c -o thunk.o thunk.c
thunk.c: In function 'x_inb':
thunk.c:40:9: error: impossible constraint in 'asm'
         __asm__ __volatile__("in" #bwl " %w1, %" #bw "0" : "=a"(value) : "Nd"(port)); \
         ^
thunk.c:44:1: note: in expansion of macro '__BUILDIO'
 __BUILDIO(b,b,char)
 ^
<builtin>: recipe for target 'thunk.o' failed
make[1]: *** [thunk.o] Error 1
make[1]: Leaving directory '/tmp/nix-build-libx86-1.1.drv-0/libx86-1.1'
Makefile:17: recipe for target 'default' failed
make: *** [default] Error 2