Introducing float64 mod for host build targets that configures ecma-number to be float64 instead of default float32.

Makefile.mk

@@ -160,6 +160,16 @@ else
      OPTION_LIBC := raw
 endif
 
+ifeq ($(filter float64,$(TARGET_MODS)), float64)
+     ifeq ($(OPTION_MCU),enable)
+      $(error MCU target doesn\'t support float64)
+     endif
+
+     OPTION_FLOAT64 := enable
+else
+     OPTION_FLOAT64 := disable
+endif
+
 ifeq ($(filter sanitize,$(TARGET_MODS)), sanitize)
      ifeq ($(OPTION_LIBC),musl)
       $(error ASAN and LIBC_MUSL are mutually exclusive)
@@ -335,6 +345,10 @@ ifeq ($(OPTION_NDEBUG),enable)
  DEFINES_JERRY += -DJERRY_NDEBUG
 endif
 
+ifeq ($(OPTION_FLOAT64),enable)
+  DEFINES_JERRY += -DCONFIG_ECMA_NUMBER_TYPE=CONFIG_ECMA_NUMBER_FLOAT64
+endif
+
 ifeq ($(OPTION_MCU),disable)
  MACHINE_TYPE=$(shell uname -m)
  ifeq ($(MACHINE_TYPE),x86_64)