Change data tag to __fstr__ for improved filtering in linker script.

This also accommodates use within templated code, where GCC ignores section attribute.

Author: mikee47

map.rst

@@ -101,12 +101,12 @@ The macro in the first example above produces a structure like this::
    constexpr const struct {
       ObjectBase object;
       MapPair<int, String> data[2];
-   } fstr_data_intmap PROGMEM = {
+   } __fstr__intmap PROGMEM = {
       {16},
       {35, &content1},
       {180, &content2},
    };
-   const Map<int, String>& intmap = fstr_data_intmap.object.as<Map<int, String>>();
+   const Map<int, String>& intmap = __fstr__intmap.object.as<Map<int, String>>();
 
 Note: ``FSTR::`` namespace qualifier omitted for clarity.
 

src/include/FlashString/Object.hpp

@@ -46,7 +46,7 @@
 /**
  * @brief Provide internal name for generated flash string structures
  */
-#define FSTR_DATA_NAME(name) fstr_data_##name
+#define FSTR_DATA_NAME(name) __fstr__##name
 
 /**
  * @brief Given an Object& reference, return a pointer to the actual object

src/include/FlashString/String.hpp

@@ -42,8 +42,8 @@ typedef const __FlashStringHelper* flash_string_t;
  */
 #define FS_PTR(str)                                                                                                    \
 	(__extension__({                                                                                                   \
-		static DEFINE_FSTR_DATA(struc, str);                                                                           \
-		static_cast<const FSTR::String*>(&struc.object);                                                               \
+		static DEFINE_FSTR_DATA(__fstr__, str);                                                                        \
+		static_cast<const FSTR::String*>(&__fstr__.object);                                                            \
 	}))
 
 /**

vector.rst

@@ -70,14 +70,14 @@ The above example generates a structure like this::
    const struct {
       ObjectBase object;
       String* entries[4];
-   } fstr_data_myTable PROGMEM = {
+   } __fstr__myTable PROGMEM = {
       {16},
       &str1,
       &str2,
       nullptr,
       &str3,
    };
-   const Vector<String>& myTable PROGMEM = fstr_data_myTable.as<Vector<String>>();
+   const Vector<String>& myTable PROGMEM = __fstr__myTable.as<Vector<String>>();
 
 Note: ``FSTR::`` namespace qualifier omitted for clarity.