Fix build for host - getCpuFreqMHz there was also in conflict with getCycleCount, using F_CPU:

tests/host/common/mock.h:#define F_CPU 80000000 (!)

Author: dok-net

cores/esp8266/Esp.h

@@ -157,7 +157,7 @@ class EspClass {
         uint8_t getBootVersion();
         uint8_t getBootMode();
 
-#if !defined(CORE_MOCK) && defined(F_CPU)
+#if defined(F_CPU)
         constexpr uint8_t getCpuFreqMHz() const
         {
             return clockCyclesPerMicrosecond();
@@ -166,7 +166,6 @@ class EspClass {
         uint8_t getCpuFreqMHz();
 #endif
 
-
         uint32_t getFlashChipId();
         uint8_t getFlashChipVendorId();
 

tests/host/common/MockEsp.cpp

@@ -118,11 +118,6 @@ uint32_t EspClass::getFreeSketchSpace()
   return 4 * 1024 * 1024;
 }
 
-uint8_t EspClass::getCpuFreqMHz()
-{
-  return F_CPU / 1000000;
-}
-
 const char *EspClass::getSdkVersion()
 {
   return "2.5.0";