fix: patch Corrade strerror_r for musl libc compatibility

musl only provides the XSI strerror_r (returns int). Corrade's
ErrorString.cpp falls into the GNU branch (expects char*) when
_GNU_SOURCE is defined by GCC even on musl targets, causing a compile
error: "invalid conversion from int to const char*".

Add a portability patch that extends the existing POSIX branch condition
to also cover non-glibc Linux (detected via __linux__ && !__GLIBC__),
so musl builds use the int-returning XSI variant that actually exists.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: leoparente

conan/corrade/conandata.yml

@@ -2,3 +2,9 @@ sources:
   "cci.20260327":
     sha256: d8f30e9a857172003b6b02304783f40e8038c36e4127a0cfec7fe14f41c13fd4
     url: https://github.com/mosra/corrade/archive/22e7ffc6fcdeaa0df96e0d8b3d482ad6abe7dc36.tar.gz
+
+patches:
+  "cci.20260327":
+    - patch_file: "patches/0001-fix-strerror_r-musl-compat.patch"
+      patch_description: "Fix strerror_r usage for non-glibc Linux (musl): always use POSIX XSI variant"
+      patch_type: "portability"

conan/corrade/patches/0001-fix-strerror_r-musl-compat.patch

@@ -0,0 +1,12 @@
+--- a/src/Corrade/Utility/Implementation/ErrorString.cpp
++++ b/src/Corrade/Utility/Implementation/ErrorString.cpp
+@@ -61,7 +61,8 @@ void printErrnoErrorString(Debug& debug, const int error) {
+        the buffer. Sigh. */
+     /** @todo might want to add CORRADE_TARGET_BSD covering all three variants,
+         there's no overarching BSD define present on all BSDs :( */
+-    #if ((_POSIX_C_SOURCE >= 200112L) && !_GNU_SOURCE) || defined(CORRADE_TARGET_EMSCRIPTEN) || defined(CORRADE_TARGET_APPLE) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__)
++    /* Also include non-glibc Linux (e.g. musl) which always provides only the XSI variant returning int */
++    #if ((_POSIX_C_SOURCE >= 200112L) && !_GNU_SOURCE) || defined(CORRADE_TARGET_EMSCRIPTEN) || defined(CORRADE_TARGET_APPLE) || defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || (defined(__linux__) && !defined(__GLIBC__))
+     char string[256];
+     CORRADE_INTERNAL_ASSERT_OUTPUT(strerror_r(error, string, Containers::arraySize(string)) == 0);
+     #else