bootstat: comment out duplicate entries in kBootReasonMap

Two entries can be reused. The third "unknown" entry is not really
a duplicate since the kUnknownBootReason is not checked.  Duplicate
entries reused in the future, should have
analysis/uma/configs/clearcut/TRON/histograms.xml updated first.

Test: boot_reason_test.sh
Change-Id: If2071a18160dc2c93e851fecc6b8c11fc76c9845

bootstat/bootstat.cpp

@@ -139,7 +139,7 @@ constexpr int32_t kUnknownBootReason = 1;
 // values.
 const std::map<std::string, int32_t> kBootReasonMap = {
     {"empty", kEmptyBootReason},
-    {"unknown", kUnknownBootReason},
+    {"__BOOTSTAT_UNKNOWN__", kUnknownBootReason},
     {"normal", 2},
     {"recovery", 3},
     {"reboot", 4},
@@ -199,7 +199,7 @@ const std::map<std::string, int32_t> kBootReasonMap = {
     {"cold", 56},
     {"hard", 57},
     {"warm", 58},
-    {"recovery", 59},
+    // {"recovery", 59},  // Duplicate of enum 3 above. Immediate reuse possible.
     {"thermal-shutdown", 60},
     {"shutdown,thermal", 61},
     {"shutdown,battery", 62},
@@ -230,7 +230,7 @@ const std::map<std::string, int32_t> kBootReasonMap = {
     {"shutdown,thermal,battery", 87},
     {"reboot,its_just_so_hard", 88},  // produced by boot_reason_test
     {"reboot,Its Just So Hard", 89},  // produced by boot_reason_test
-    {"usb", 90},
+    // {"usb", 90},  // Duplicate of enum 80 above. Immediate reuse possible.
     {"charge", 91},
     {"oem_tz_crash", 92},
     {"uvlo", 93},