Refactor to fix Clang warnings Signed-off-by: Tomasz Michalak <tmichalak@antmicro.com>

diff --git a/sdc-plugin/buffers.cc b/sdc-plugin/buffers.cc
index cb54743..919de28 100644
--- a/sdc-plugin/buffers.cc
+++ b/sdc-plugin/buffers.cc

@@ -35,7 +35,7 @@
 
 void Pll::CheckInputClockPeriod(RTLIL::Cell* cell, float input_clock_period) {
     float abs_diff = fabs(ClkinPeriod() - input_clock_period);
-    bool approx_equal = abs_diff < max(ClkinPeriod(), input_clock_period) * 10 * std::numeric_limits<float>::epsilon();
+    bool approx_equal = abs_diff < std::max(ClkinPeriod(), input_clock_period) * 10 * std::numeric_limits<float>::epsilon();
     if (!approx_equal) {
 	log_cmd_error(
 	    "CLKIN[1/2]_PERIOD doesn't match the virtual clock constraint "

diff --git a/sdc-plugin/clocks.cc b/sdc-plugin/clocks.cc
index 0a1572a..c177f6a 100644
--- a/sdc-plugin/clocks.cc
+++ b/sdc-plugin/clocks.cc

@@ -18,6 +18,7 @@
 #include "clocks.h"
 #include <cassert>
 #include <cmath>
+#include <regex>
 #include "kernel/log.h"
 #include "kernel/register.h"
 #include "propagation.h"

diff --git a/sdc-plugin/clocks.h b/sdc-plugin/clocks.h
index f5b491c..67ca272 100644
--- a/sdc-plugin/clocks.h
+++ b/sdc-plugin/clocks.h

@@ -18,7 +18,6 @@
 #ifndef _CLOCKS_H_
 #define _CLOCKS_H_
 
-#include <unordered_map>
 #include <vector>
 #include "buffers.h"
 #include "kernel/rtlil.h"

diff --git a/sdc-plugin/propagation.h b/sdc-plugin/propagation.h
index bc7a6d2..6774062 100644
--- a/sdc-plugin/propagation.h
+++ b/sdc-plugin/propagation.h

@@ -26,6 +26,7 @@
    public:
     Propagation(RTLIL::Design* design, Pass* pass)
         : design_(design), pass_(pass) {}
+    virtual ~Propagation(){}
 
     virtual void Run(Clocks& clocks) = 0;
     std::vector<RTLIL::Wire*> FindSinkWiresForCellType(