catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If8dcf70005aebd4ca633b91d6f96badf4a5cd326
diff --git a/callout.cpp b/callout.cpp
index 6c96455..3f409f9 100644
--- a/callout.cpp
+++ b/callout.cpp
@@ -161,7 +161,7 @@
 
         iarchive(*this);
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>(e.what());
         log<level::ERR>("Failed trying to restore a Callout object",
diff --git a/manager.cpp b/manager.cpp
index fdd1540..aa8d5e0 100644
--- a/manager.cpp
+++ b/manager.cpp
@@ -273,7 +273,7 @@
         {
             id = std::stoul(f.path().filename());
         }
-        catch (std::exception& e)
+        catch (const std::exception& e)
         {
             log<level::ERR>("Invalid IBM logging callout save file. Deleting",
                             entry("FILE=%s", f.path().c_str()));
diff --git a/policy_find.cpp b/policy_find.cpp
index 191240e..bf58301 100644
--- a/policy_find.cpp
+++ b/policy_find.cpp
@@ -284,7 +284,7 @@
                 return value;
             }
         }
-        catch (std::exception& e)
+        catch (const std::exception& e)
         {
             using namespace phosphor::logging;
             log<level::ERR>("Invalid PROCEDURE value found",
diff --git a/policy_table.cpp b/policy_table.cpp
index df32d59..f77bc6e 100644
--- a/policy_table.cpp
+++ b/policy_table.cpp
@@ -68,7 +68,7 @@
 
         loaded = true;
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>("Failed loading policy table json file",
                         entry("FILE=%s", jsonFile.c_str()),