lang/pocl: drop pkg-message + minor style and whitespace fixes

- Do not hardcode architectures in ONLY_FOR_ARCHS_REASON, derive
  them from ONLY_FOR_ARCHS instead (this also takes care of the
  missing Oxford comma)
- Remove the pkg-message file since the issue it talks about had
  been fixed in 2015; it also had slightly incorrect wording and
  several EOL whitespace bugs

lang/pocl/Makefile

@@ -10,7 +10,7 @@ LICENSE=	MIT
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
 ONLY_FOR_ARCHS=	aarch64 amd64 i386 powerpc64 powerpc64le
-ONLY_FOR_ARCHS_REASON=	only tested on aarch64, amd64, i386, powerpc64 and powerpc64le
+ONLY_FOR_ARCHS_REASON=	only tested on ${ONLY_FOR_ARCHS:tW:S/ /, /g}
 
 BUILD_DEPENDS=	llvm${LLVM_VERSION}>=10:devel/llvm${LLVM_VERSION} \
 		opencl>=2.2:devel/opencl

lang/pocl/pkg-descr

@@ -1,18 +1,15 @@
-Portable OpenCL (pocl)
-----------------------
-
 Portable OpenCL aims to be an efficient open source (MIT-licensed)
 implementation of the OpenCL 1.2 standard.
 
 In addition to producing an easily portable open source OpenCL
 implementation, another major goal of the project is improving
 performance portability of OpenCL programs with compiler
 optimizations, reducing the need for target-dependent manual
-optimizations. At the core of pocl is a set of LLVM passes
-used to statically parallelize multiple work-items with the kernel
+optimizations. At the core of POCL is a set of LLVM passes used
+to statically parallelize multiple work-items with the kernel
 compiler, even in the presence of work-group barriers. This enables
 parallelization of the fine-grained static concurrency in the work
-groups in multiple ways (SIMD, VLIW, superscalar,...).
+groups in multiple ways (SIMD, VLIW, superscalar, ...).
 
 The code base is modularized to allow easy adding of new "device drivers"
 in the host-device layer. A generic multithreaded "target driver" is