hdf5: Fix compiler identification for warning flags (#24627)

* Fix compiler test

Use `self.spec.satisfies` on compiler to determine if a flag should be
applied or not.  This approach avoids issues with the strings `gcc`
or `clang` appearing in the full path to the compiler executables, as
happens with spack-installed compilers (e.g. `nvhpc%gcc`).

* Limit compiler name search to last path component

@skosukhin pointed out that the cflag modification should happen for any
clang or gcc compiler, regardless of what compiler spec provides them.
This commit reverts to searching for a compiler name containing "gcc"
or "clang", but limits the search to the last path component, which
avoids matching spack-installed compilers built with gcc (e.g.
`nvhpc%gcc`), which will have "gcc" in the compiler path.

* Use `os.path` rather than `pathlib`

Co-authored-by: Paul Henning <phenning@lanl.gov>

var/spack/repos/builtin/packages/hdf5/package.py

@@ -187,7 +187,8 @@ def flag_handler(self, name, flags):
         cmake_flags = []
 
         if name == "cflags":
-            if "clang" in self.compiler.cc or "gcc" in self.compiler.cc:
+            cc_name = os.path.basename(self.compiler.cc)
+            if "clang" in cc_name or "gcc" in cc_name:
                 # Quiet warnings/errors about implicit declaration of functions
                 # in C99:
                 cmake_flags.append("-Wno-implicit-function-declaration")