Fix boost process call for SEL Clear

The boost::process::system call to journalctl for SEL clear was failing
from not finding the 'journalctl' command.  This change add a
boost::process::search_path to search for the full path to journalctl
which fixes the system call.

Tested: Before the change SEL Clear returned 0xFF.  After the change
SEL Clear returns successfully and executes the journalctl call.

Change-Id: I03510608a705c034638a1cabf71f5c2ed24b14ec
Signed-off-by: Jason M. Bills <jason.m.bills@linux.intel.com>
diff --git a/src/storagecommands.cpp b/src/storagecommands.cpp
index 24b3005..ad9d182 100644
--- a/src/storagecommands.cpp
+++ b/src/storagecommands.cpp
@@ -1041,11 +1041,13 @@
 
     // Clear the SEL by by rotating the journal to start a new file then
     // vacuuming to keep only the new file
-    if (boost::process::system("journalctl", "--rotate") != 0)
+    if (boost::process::system(boost::process::search_path("journalctl"),
+                               "--rotate") != 0)
     {
         return IPMI_CC_UNSPECIFIED_ERROR;
     }
-    if (boost::process::system("journalctl", "--vacuum-files=1") != 0)
+    if (boost::process::system(boost::process::search_path("journalctl"),
+                               "--vacuum-files=1") != 0)
     {
         return IPMI_CC_UNSPECIFIED_ERROR;
     }