windows: guard static_assert with __STDC_VERSION__ for C99 compatibility (#810)

windows/hidapi_descriptor_reconstruct.h uses static_assert() to
sanity-check the layout of hid_pp_link_collection_node_. static_assert
was added to <assert.h> in C11; building with -std=c99 (e.g.
set(CMAKE_C_STANDARD 99) in a parent project) on mingw/gcc fails at
that line because the identifier is undeclared.

The assertion's preceding comment describes it as a "risk-reduction
measure" rather than a strict requirement, so guard it with
`#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L`.
C11/C17/C23 toolchains still get the compile-time check; older
standards (and MSVC default C mode, where __STDC_VERSION__ is not
typically set that high) skip it and build cleanly.

Closes: #764

Assisted-by: Claude:claude-opus-4.7

Author: Youw

windows/hidapi_descriptor_reconstruct.h

@@ -124,8 +124,12 @@ typedef struct hid_pp_link_collection_node_ {
 //       Although very unlikely, it might still be possible that the compiler creates a memory layout that is
 //       not binary compatile.
 //       Other structs are not checked at the time of writing.
+// static_assert was added to <assert.h> in C11; skip this check when the
+// translation unit is compiled as C99 or earlier, where it is unavailable.
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
 static_assert(sizeof(struct hid_pp_link_collection_node_) == 16,
     "Size of struct hid_pp_link_collection_node_ not as expected. This might break binary compatibility");
+#endif
 
 typedef struct hidp_unknown_token_ {
 	UCHAR Token; /* Specifies the one-byte prefix of a global item. */