Fix klocwork issues

Klockwork reports these issues:
1. phosphor-watchdog/src/mainapp.cpp:119 | main()
   'fallbackAlways' is used uninitialized in this function.
2. phosphor-watchdog/src/mainapp.cpp:129 | main()
   'watchPostcodes' is used uninitialized in this function.
3. phosphor-watchdog/src/mainapp.cpp:80 | main()
   'continueAfterTimeout' is used uninitialized in this function.

This commit adds default values to resolve these issues.

Tested: Watchdog service worked well.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Change-Id: Ib88afb60e801c3f90e039cca99dca5409e896fc1
diff --git a/src/mainapp.cpp b/src/mainapp.cpp
index 063b8d3..1654eca 100644
--- a/src/mainapp.cpp
+++ b/src/mainapp.cpp
@@ -76,7 +76,7 @@
                    "Ex: xyz.openbmc_project.State.Watchdog.Host")
         ->required()
         ->group(serviceGroup);
-    bool continueAfterTimeout;
+    bool continueAfterTimeout{false};
     app.add_flag("-c,--continue", continueAfterTimeout,
                  "Continue daemon after watchdog timeout")
         ->group(serviceGroup);
@@ -115,7 +115,7 @@
             ->group(fallbackGroup);
     fallbackIntervalOpt->needs(fallbackActionOpt);
     fallbackActionOpt->needs(fallbackIntervalOpt);
-    bool fallbackAlways;
+    bool fallbackAlways{false};
     app.add_flag("-e,--fallback_always", fallbackAlways,
                  "Enables the "
                  "watchdog even when disabled by the dbus interface. "
@@ -125,7 +125,7 @@
         ->needs(fallbackIntervalOpt);
 
     // Should we watch for postcodes
-    bool watchPostcodes;
+    bool watchPostcodes{false};
     app.add_flag("-w,--watch_postcodes", watchPostcodes,
                  "Should we reset the time remaining any time a postcode "
                  "is signaled.");