Include cmath, needed for FP std::abs.

Change-Id: I0275b8090c96a2762597c62ecfd9dd422fd731a7
Reviewed-on: https://weave-review.googlesource.com/1470
Reviewed-by: Vitaly Buka <vitalybuka@google.com>

src/commands/schema_utils.h

diff --git a/src/commands/schema_utils.h b/src/commands/schema_utils.h
index 826bab8..0c1d1b3 100644
--- a/src/commands/schema_utils.h
+++ b/src/commands/schema_utils.h
@@ -5,6 +5,7 @@
 #ifndef LIBWEAVE_SRC_COMMANDS_SCHEMA_UTILS_H_
 #define LIBWEAVE_SRC_COMMANDS_SCHEMA_UTILS_H_
 
+#include <cmath>
 #include <limits>
 #include <map>
 #include <memory>