Remove various file reading (Linux specific) paths

This removes a bunch of libc stuff from HelloWorld,
in addition to removing the actual file opening.

src/coreclr/gc/unix/gcenv.unix.cpp

@@ -1263,6 +1263,8 @@ uint64_t GetAvailablePhysicalMemory()
     sysctlbyname("vm.stats.vm.v_free_count", &free_count, &sz, NULL, 0);
 
     available = (inactive_count + laundry_count + free_count) * sysconf(_SC_PAGESIZE);
+#elif defined(TARGET_WASM)
+    available = sysconf(SYSCONF_PAGES) * sysconf(_SC_PAGE_SIZE);
 #else // Linux
     static volatile bool tryReadMemInfo = true;
 

src/coreclr/gc/wasm/gcenv.wasm.cpp

@@ -4,7 +4,6 @@
 #include "common.h"
 #include "gcenv.h"
 
-
 // Flush write buffers of processors that are executing threads of the current process - a NOP for Wasm
 void GCToOSInterface::FlushProcessWriteBuffers()
 {
@@ -118,3 +117,24 @@ bool GCToOSInterface::VirtualReset(void* address, size_t size, bool unlock)
 {
     return false;
 }
+
+//
+// CPU and memory limits - not avaliable on WASM (yet).
+//
+void InitializeCGroup()
+{
+}
+
+void CleanupCGroup()
+{
+}
+
+size_t GetRestrictedPhysicalMemoryLimit()
+{
+    return 0; // 'Unlimited'.
+}
+
+bool GetPhysicalMemoryUsed(size_t* val)
+{
+    return false; // 'Unknown'.
+}

src/coreclr/nativeaot/Runtime/CMakeLists.txt

@@ -163,12 +163,15 @@ else()
   )
 
   if (CLR_CMAKE_TARGET_ARCH_WASM)
+    list(REMOVE_ITEM COMMON_RUNTIME_SOURCES
+      ${GC_DIR}/unix/cgroup.cpp
+      unix/PalCreateDump.cpp
+    )
     list(APPEND COMMON_RUNTIME_SOURCES
       ${GC_DIR}/wasm/gcenv.wasm.cpp
       wasm/PalCreateDump.cpp
-      unix/cgroupcpu.cpp
+      wasm/cgroupcpu.cpp
     )
-    list(REMOVE_ITEM COMMON_RUNTIME_SOURCES unix/PalCreateDump.cpp)
   endif()
 
   list(APPEND FULL_RUNTIME_SOURCES

src/coreclr/nativeaot/Runtime/wasm/cgroupcpu.cpp

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#include <cstdint>
+
+//
+// No CPU or memory limits on WASM as yet.
+//
+void InitializeCpuCGroup()
+{
+}
+
+bool GetCpuLimit(uint32_t* val)
+{
+    return false;
+}