import use of __PROG_TYPES_COMPAT__ define for compatibility with old arduino code (#4619)

restrict usage of deprecated typedefs "prog_*", and cast "pgm_read_*"'s address parameters to "const void*"  only when __PROG_TYPES_COMPAT__ is defined.
also add <avr/pgmspace.h> compatibility

Author: d-a-v

Diff for: cores/esp8266/avr/pgmspace.h

@@ -0,0 +1 @@
+#include "../pgmspace.h"

Diff for: cores/esp8266/pgmspace.h

@@ -29,6 +29,8 @@ extern "C" {
 
 #define _SFR_BYTE(n) (n)
 
+#ifdef __PROG_TYPES_COMPAT__
+
 typedef void prog_void;
 typedef char prog_char;
 typedef unsigned char prog_uchar;
@@ -39,6 +41,8 @@ typedef uint16_t prog_uint16_t;
 typedef int32_t prog_int32_t;
 typedef uint32_t prog_uint32_t;
 
+#endif // defined(__PROG_TYPES_COMPAT__)
+
 #define SIZE_IRRELEVANT 0x7fffffff
 
 // memchr_P and memrchr_P are not implemented due to danger in its use, and
@@ -112,8 +116,13 @@ static inline uint16_t pgm_read_word_inlined(const void* addr) {
 }
 
 // Make sure, that libraries checking existence of this macro are not failing
+#ifdef __PROG_TYPES_COMPAT__
+#define pgm_read_byte(addr) pgm_read_byte_inlined((const void*)(addr))
+#define pgm_read_word(addr) pgm_read_word_inlined((const void*)(addr))
+#else
 #define pgm_read_byte(addr) pgm_read_byte_inlined(addr)
 #define pgm_read_word(addr) pgm_read_word_inlined(addr)
+#endif
 
 #else //__ets__
 #define pgm_read_byte(addr)     (*reinterpret_cast<const uint8_t*>(addr))