openpower-pels: clean up various compile warnings

Compile warnings observed when compiling parts of the
openpower-pels (or corresponding tests) under stricter
compiler warning flags of Meson.

Issues fixed:
    - many unused parameters
    - invalid case fall-through
    - excess semi-colons
    - incorrect 'const' on return-by-value type
    - removal of variable length array in test case
    - uncaught return from 'system' call in test case

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I8af69184042cf8661d1307a02ecf3afcab4724a1
diff --git a/extensions/openpower-pels/repository.cpp b/extensions/openpower-pels/repository.cpp
index e044e1d..1ab774a 100644
--- a/extensions/openpower-pels/repository.cpp
+++ b/extensions/openpower-pels/repository.cpp
@@ -593,7 +593,7 @@
     };
 
     // When counting PELs, count every PEL
-    IsPELTypeFunc isAnyPEL = [](const PELAttributes& pel) { return true; };
+    IsPELTypeFunc isAnyPEL = [](const PELAttributes& /*pel*/) { return true; };
 
     // Check all 4 categories, which will result in at most 90%
     // usage (15 + 30 + 15 + 30).
@@ -649,7 +649,7 @@
                         return pel.hostState == TransmissionState::sent;
                     },
 
-                    [](const auto& pel) { return true; }};
+                    [](const auto& /*pel*/) { return true; }};
 
     for (const auto& stateCheck : stateChecks)
     {