command results: yum install libX11-devel.i386 libX11-devel.x86_64 -y
Code:
[root@cpanel ImageMagick-6.6.6-7]# yum install libX11-devel.i386 libX11-devel.x86_64 -y
Loading "fastestmirror" plugin
Setting up Install Process
Setting up repositories
update 100% |=========================| 951 B 00:00
base 100% |=========================| 1.1 kB 00:00
addons 100% |=========================| 951 B 00:00
extras 100% |=========================| 1.1 kB 00:00
Loading mirror speeds from cached hostfile
Reading repository metadata in from local files
primary.xml.gz 100% |=========================| 529 kB 00:00
update : ################################################## 1211/1211
primary.xml.gz 100% |=========================| 715 kB 00:00
base : ################################################## 1844/1844
primary.xml.gz 100% |=========================| 192 B 00:00
primary.xml.gz 100% |=========================| 40 kB 00:00
extras : ################################################## 146/146
Excluding Packages in global exclude list
Finished
Parsing package install arguments
No Match for argument: libX11-devel.i386
No Match for argument: libX11-devel.x86_64
Nothing to do
[root@cpanel ImageMagick-6.6.6-7]#
Same error at MAKE command 
Code:
[root@cpanel ImageMagick-6.6.6-7]# make
make all-am
make[1]: Entering directory `/ImageMagick-6.6.6-7'
CCLD magick/libMagickCore.la
/usr/bin/ld: skipping incompatible /usr/X11R6/lib/libX11.so when searching for -lX11
/usr/bin/ld: skipping incompatible /usr/X11R6/lib/libX11.a when searching for -lX11
/usr/bin/ld: cannot find -lX11
collect2: ld returned 1 exit status
make[1]: *** [magick/libMagickCore.la] Error 1
make[1]: Leaving directory `/ImageMagick-6.6.6-7'
make: *** [all] Error 2
[root@cpanel ImageMagick-6.6.6-7]#