webgpu: fix two things wrt linux build (#8881)

 - Added an explicit link flag for libxcb in backend/CMakeLists.txt
 - Made a string func inline, otherwise we'd get duplicate
   definition error during linking.

FIXES=419788369

Author: poweifeng

filament/backend/CMakeLists.txt

@@ -505,11 +505,20 @@ if (FILAMENT_SUPPORTS_WEBGPU)
     target_compile_definitions(${TARGET} PRIVATE $<$<BOOL:${FILAMENT_WEBGPU_IMMEDIATE_ERROR_HANDLING}>:FILAMENT_WEBGPU_IMMEDIATE_ERROR_HANDLING>)
 endif()
 
+# ==================================================================================================
+# Linker flags
+# ==================================================================================================
+
 target_link_libraries(${TARGET} PRIVATE
-        ${OSMESA_LINKER_FLAGS}
         $<$<AND:$<PLATFORM_ID:Linux>,$<CONFIG:Release>>:${LINUX_LINKER_OPTIMIZATION_FLAGS}>
 )
 
+if (LINUX AND FILAMENT_SUPPORTS_WEBGPU)
+    # Unclear why this needs to be explicit while other linux libs do not, but it is necessary for
+    # WebGPU to build on linux.
+    target_link_libraries(${TARGET} PRIVATE -lxcb)
+endif()
+
 # ==================================================================================================
 # Installation
 # ==================================================================================================

filament/backend/src/webgpu/WebGPUStrings.h

@@ -101,7 +101,7 @@ template<typename WebGPUPrintable>
     return out.str();
 }
 
-[[nodiscard]] std::string adapterInfoToString(wgpu::AdapterInfo const& info) {
+[[nodiscard]] inline std::string adapterInfoToString(wgpu::AdapterInfo const& info) {
     std::stringstream out;
     out << "vendor (" << info.vendorID << ") '" << info.vendor
         << "' device (" << info.deviceID << ") '" << info.device