enable MKCOMPATX11

[zerous <zerous@nocebo.space>]

Hi,

I am working on porting Wine to amd64 and would like to have 32-bit X
libs on amd64 for 32-bit wine. I was wondering if we could enable
MKCOMPATX11 by default on amd64 for the same.  I tried building NetBSD
userland with and without MKCOMPATX11 enabled and found the difference
in build times to be negligible.

w/o MKCOMPATX11
build time: 13563.25s real 20906.01s user  5062.78s system

w/ MKCOMPATX11
build time: 13666.99s real 21029.73s user  5076.46s system

My environment:
$ uname -a
NetBSD mode64 8.99.43 NetBSD 8.99.43 (W2) #0: Sun Jun  9 14:20:32 CEST 2019  zer@mode64:/usr/src/sys/arch/amd64/compile/W2 amd64
$ cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 23
model name	: Intel(R) Core(TM)2 Duo CPU     E7500  @ 2.93GHz
stepping	: 10
cpu MHz		: 2926.18
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp    		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dtherm
clflush size	: 64

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model	        : 23
model name      : Intel(R) Core(TM)2 Duo CPU     E7500  @ 2.93GHz
stepping        : 10
cpu MHz	        : 2926.27
apicid	        : 1
initial apicid  : 1
fpu	        : yes
fpu_exception   : yes
cpuid level     : 13
wp    	        : yes
flags	      	: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dtherm
clflush size	: 64

-- 
zer