LibCore: Add System::physical_memory_bytes()

Author: https://github.com/gmta
Commit: https://github.com/LadybirdBrowser/ladybird/commit/9515290fde3
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1681

Userland/Libraries/LibCore/System.cpp

@@ -1751,6 +1751,11 @@ unsigned hardware_concurrency()
     return sysconf(_SC_NPROCESSORS_ONLN);
 }
 
+u64 physical_memory_bytes()
+{
+    return sysconf(_SC_PHYS_PAGES) * PAGE_SIZE;
+}
+
 ErrorOr<String> resolve_executable_from_environment(StringView filename, int flags)
 {
     if (filename.is_empty())

Userland/Libraries/LibCore/System.h

@@ -283,6 +283,7 @@ ErrorOr<void> posix_fallocate(int fd, off_t offset, off_t length);
 #endif
 
 unsigned hardware_concurrency();
+u64 physical_memory_bytes();
 
 ErrorOr<String> resolve_executable_from_environment(StringView filename, int flags = 0);