metric-ipmi-blobs: adding tmpfs

Adding tmpfs metric coverage to pre-ttf machines

Tested:
```
df -h
Filesystem                Size      Used Available Use% Mounted on
dev                     468.9M         0    468.9M   0% /dev
tmpfs                   469.9M     12.6M    457.3M   3% /run
/dev/mtdblock4           20.6M     20.6M         0 100% /run/initramfs/ro
/dev/mtdblock6            3.0M    436.0K      2.6M  14% /run/initramfs/rw
cow                       3.0M    436.0K      2.6M  14% /
tmpfs                   469.9M      8.0K    469.9M   0% /dev/shm
tmpfs                   469.9M         0    469.9M   0% /tmp
tmpfs                   469.9M     40.0K    469.8M   0% /var/volatile
tmpfs                   469.9M     12.6M    457.3M   3% /var/lib/systemd/coredump
```

Change-Id: I50c763707268252ed51a903d8b7e02543dab6166
Signed-off-by: Abby <buchmana@google.com>
diff --git a/subprojects/metrics-ipmi-blobs/metric.cpp b/subprojects/metrics-ipmi-blobs/metric.cpp
index bbff3ef..d3fe0e2 100644
--- a/subprojects/metrics-ipmi-blobs/metric.cpp
+++ b/subprojects/metrics-ipmi-blobs/metric.cpp
@@ -409,14 +409,24 @@
     getStorageMetric(bool& use) noexcept
 {
     bmcmetrics_metricproto_BmcDiskSpaceMetric ret = {};
-    struct statvfs fiData;
-    if (statvfs("/", &fiData) < 0)
+    struct statvfs rwFiData, tmpFiData;
+    if (statvfs("/", &rwFiData) < 0)
     {
         log<level::ERR>("Could not call statvfs");
     }
     else
     {
-        ret.rwfs_kib_available = (fiData.f_bsize * fiData.f_bfree) / 1024;
+        ret.rwfs_kib_available = (rwFiData.f_bsize * rwFiData.f_bfree) / 1024;
+        use = true;
+    }
+    if (statvfs("/tmp", &tmpFiData) < 0)
+    {
+        log<level::ERR>("Could not call statvfs");
+    }
+    else
+    {
+        ret.tmpfs_kib_available =
+            (tmpFiData.f_bsize * tmpFiData.f_bfree) / 1024;
         use = true;
     }
     return ret;
diff --git a/subprojects/metrics-ipmi-blobs/metricblob.proto b/subprojects/metrics-ipmi-blobs/metricblob.proto
index 4d3038f..1af85e8 100644
--- a/subprojects/metrics-ipmi-blobs/metricblob.proto
+++ b/subprojects/metrics-ipmi-blobs/metricblob.proto
@@ -34,6 +34,7 @@
 
 message BmcDiskSpaceMetric {
   int32 rwfs_kib_available = 1;  // Free space in RWFS in KiB
+  int32 tmpfs_kib_available = 2;  // Free space in TMPFS in KiB
 }
 
 // The following messages use string tables to save space