fix(libsodium): disable C11 Annex K declarations to fix build with picolibc

Upstream libsodium's utils.c defines __STDC_WANT_LIB_EXT1__=1, which
requests C11 Annex K bounds-checking types (errno_t, rsize_t) from the
C library. With ESP-IDF v6.0+ (which uses picolibc instead of newlib),
this can cause build failures when sys/_types.h is transitively included
by other component headers before utils.c sets the macro. The include
guard in sys/_types.h prevents re-inclusion, so the conditional Annex K
type definitions (__errno_t, __rsize_t) are never reached.

Set __STDC_WANT_LIB_EXT1__=0 as a compile definition so the flag is
applied before any header is processed, avoiding the issue regardless
of include order. This is safe because libsodium does not use any
Annex K functions on ESP-IDF.

Author: hrushikesh430

libsodium/CMakeLists.txt

@@ -139,6 +139,7 @@ target_compile_definitions(${COMPONENT_LIB} PRIVATE
     HAVE_WEAK_SYMBOLS
     __STDC_LIMIT_MACROS
     __STDC_CONSTANT_MACROS
+    __STDC_WANT_LIB_EXT1__=0
     )
 
 # patch around warnings in third-party files