Ensure embedded FlatBuffers binary schemas are 8-byte aligned

In `src/idl_gen_cpp.cpp`, code generated by `flatc --bfbs-gen-embed` emits `static const uint8_t bfbsData[...] = { ... };`. Because `uint8_t` has 1-byte alignment, the array may be placed at an unaligned address in `.rodata`, triggering alignment traps under Clang UBSan on Arm when accessed via FlatBuffers root accessors.

Add `alignas(uint64_t)` to the generated `bfbsData` array declaration in `GenerateBinarySchema` so embedded binary schemas are 8-byte aligned across all architectures.

PiperOrigin-RevId: 1003962636

include/flatbuffers/base.h

@@ -271,7 +271,7 @@ namespace flatbuffers {
   #if (defined(_MSC_VER) && _MSC_VER >= 1800) || \
       (defined(__ANDROID__) && defined(__ANDROID_API__) && __ANDROID_API__>= 26) || \
       (defined(_XOPEN_VERSION) && (_XOPEN_VERSION >= 700)) && \
-      !defined(__Fuchsia__)
+      !defined(__Fuchsia__) && (!defined(__linux__) || defined(__GLIBC__))
     #define FLATBUFFERS_LOCALE_INDEPENDENT 1
   #else
     #define FLATBUFFERS_LOCALE_INDEPENDENT 0

src/idl_gen_cpp.cpp

@@ -404,7 +404,7 @@ class CppGenerator : public BaseGenerator {
       code_ += "struct {{STRUCT_NAME}}BinarySchema {";
       code_ += "  static const uint8_t *data() {";
       code_ += "    // Buffer containing the binary schema.";
-      code_ += "    static const uint8_t bfbsData[" +
+      code_ += "    alignas(uint64_t) static const uint8_t bfbsData[" +
                NumToString(parser_.builder_.GetSize()) + "] = {";
       code_ += binary_schema_hex_text;
       code_ += "    };";