hsa-rocr-dev, llvm-amdgpu: change dependency libelf to elf (#29408)

* hsa-rocr-dev, llvm-amdgpu: change dependency libelf to elf

Change the libelf dependency to the virtual elf for two rocm packages.
This allows other packages (hpctoolkit) to combine rocm and dyninst
(with elfutils) while still being able to build rocm with libelf when
needed, eg darwin.

* add comment describing include path for libelf vs elfutils

var/spack/repos/builtin/packages/hsa-rocr-dev/package.py

@@ -4,6 +4,8 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 
+import os
+
 from spack import *
 
 
@@ -43,7 +45,7 @@ class HsaRocrDev(CMakePackage):
     # Note, technically only necessary when='@3.7: +image', but added to all
     # to work around https://github.com/spack/spack/issues/23951
     depends_on('xxd', when='+image', type='build')
-    depends_on('libelf@0.8:', type='link')
+    depends_on('elf', type='link')
 
     for ver in ['3.5.0', '3.7.0', '3.8.0', '3.9.0', '3.10.0', '4.0.0', '4.1.0',
                 '4.2.0', '4.3.0', '4.3.1', '4.5.0', '4.5.2', 'master']:
@@ -61,7 +63,11 @@ class HsaRocrDev(CMakePackage):
     def cmake_args(self):
         spec = self.spec
 
-        libelf_include = spec['libelf'].prefix.include.libelf
+        # hsa-rocr-dev wants the directory containing the header files, but
+        # libelf adds an extra path (include/libelf) compared to elfutils
+        libelf_include = os.path.dirname(
+            find_headers('libelf', spec['elf'].prefix.include, recursive=True)[0])
+
         args = [
             self.define('LIBELF_INCLUDE_DIRS', libelf_include),
             self.define_from_variant('BUILD_SHARED_LIBS', 'shared')

var/spack/repos/builtin/packages/llvm-amdgpu/package.py

@@ -63,7 +63,7 @@ class LlvmAmdgpu(CMakePackage):
     # openmp dependencies
     depends_on("perl-data-dumper", type=("build"), when='+openmp')
     depends_on("hwloc", when='+openmp')
-    depends_on('libelf', type='link', when='+openmp')
+    depends_on('elf', type='link', when='+openmp')
 
     # Will likely only be fixed in LLVM 12 upstream
     patch('fix-system-zlib-ncurses.patch', when='@3.5.0:3.8.0')