Description of problem:
pocl.spec contains

# Only armv7l is supported
# PPC support is currently broken, due to path problems
# s390(x) and aarch64 also not supported, so use ExclusiveArch
ExclusiveArch:  %{ix86} x86_64

without any upstream reference. I ran scratch builds of latest rawhide build 0.13-2.fc25 for armv7hl[1], aarch64[2], ppc64[3], ppc64le[4] and s390(x)[5].

pocl's CMakeLists.txt doesn't seem to know what to do on non-x86 arches with -DKERNELLIB_HOST_CPU_VARIANTS=distro, so I modified the spec a little:
--- pocl.spec.orig	2016-04-06 11:17:32.820212382 +0200
+++ pocl.spec	2016-04-06 11:34:19.705471171 +0200
@@ -16,7 +16,7 @@
 # Only armv7l is supported
 # PPC support is currently broken, due to path problems
 # s390(x) and aarch64 also not supported, so use ExclusiveArch
-ExclusiveArch:  %{ix86} x86_64
+#ExclusiveArch:  %{ix86} x86_64
 
 BuildRequires:  cmake
 BuildRequires:  clang clang-devel
@@ -87,7 +87,9 @@
   %cmake ../ \
     -DENABLE_ICD=1 \
     -DEXTRA_KERNEL_CXX_FLAGS="%{optflags} -std=c++11" \
+%ifarch i686 x86_64
     -DKERNELLIB_HOST_CPU_VARIANTS=distro
+%endif
     # -DENABLE_TESTSUITES=all Requires clBLAS
   %make_build
 popd

Of course, that should be improved in the upstream build system, so that we can pass -DKERNELLIB_HOST_CPU_VARIANTS=distro on all arches. Here are the results:

armv7hl builds and tests pass:
100% tests passed, 0 tests failed out of 108
Label Time Summary:
Einstein      = 133.71 sec (1 test)
hsa           =  12.69 sec (3 tests)
internal      = 959.38 sec (95 tests)
kernel        = 525.98 sec (20 tests)
regression    = 142.42 sec (33 tests)
runtime       =  42.00 sec (16 tests)
spir          =   2.55 sec (1 test)
tce           = 155.10 sec (36 tests)
workgroup     =  85.36 sec (18 tests)
Total Test time (real) = 1506.66 sec

aarch64 seems to have a build system problem that makes it pass -march=(unknown) to clang:
[...]
clang-3.8: error: the clang compiler does not support '-march=(unknown)'
[...]

ppc64 builds fine, but:
[...]
41% tests passed, 64 tests failed out of 108.
[...]

ppc64le fails with compilation errors.

The s390(x) clang build still seems to be suffering from bug 1309055.

Please remove ExclusiveArch: from the spec, replace it with:
ExcludeArch: aarch64 ppc64 ppc64le s390 s390x
for the time being, and fix/file bug reports as appropriate. I believe at least the aarch64 issue can be fixed easily. The ppc64(le) should be fixable as well, given that llvm supports these targets. Please let me know if you need any help.

Version-Release number of selected component (if applicable):
0.13-2.fc25

Additional information:
[1] http://koji.fedoraproject.org/koji/taskinfo?taskID=13573295
[2] http://arm.koji.fedoraproject.org/koji/taskinfo?taskID=3490371
[3] http://ppc.koji.fedoraproject.org/koji/taskinfo?taskID=3281474
[4] http://ppc.koji.fedoraproject.org/koji/taskinfo?taskID=3281475
[5] http://s390.koji.fedoraproject.org/koji/taskinfo?taskID=2176966