Fix incorrect definition of FPSTR() and move from pgmspace.h to WString.h (#1371) (#2961)

Author: bxparks

cores/esp32/WString.h

@@ -35,7 +35,8 @@ class StringSumHelper;
 // an abstract class used as a means to proide a unique pointer type
 // but really has no body
 class__FlashStringHelper;
-#defineF(string_literal) (reinterpret_cast<const __FlashStringHelper *>(PSTR(string_literal)))
+#defineFPSTR(pstr_pointer) (reinterpret_cast<const __FlashStringHelper *>(pstr_pointer))
+#defineF(string_literal) (FPSTR(PSTR(string_literal)))
 
 // The string class
 classString {

cores/esp32/pgmspace.h

@@ -32,7 +32,6 @@ typedef unsigned long prog_uint32_t;
 #definePROGMEM
 #definePGM_P const char *
 #definePGM_VOID_P const void *
-#defineFPSTR(p) ((const char *)(p))
 #definePSTR(s) (s)
 #define_SFR_BYTE(n) (n)