Kernel: Implement svcGetSystemInfo

This makes smealum/ctrulib@b96dd51d33 work
with Citra.

src/core/hle/svc.h

@@ -41,6 +41,35 @@ enum ArbitrationType {
 
 namespace SVC {
 
+/// Values accepted by svcGetSystemInfo's type parameter.
+enum class SystemInfoType {
+    /**
+     * Reports total used memory for all regions or a specific one, according to the extra
+     * parameter. See `SystemInfoMemUsageRegion`.
+     */
+    REGION_MEMORY_USAGE = 0,
+    /**
+     * Returns the memory usage for certain allocations done internally by the kernel.
+     */
+    KERNEL_ALLOCATED_PAGES = 2,
+    /**
+     * "This returns the total number of processes which were launched directly by the kernel.
+     * For the ARM11 NATIVE_FIRM kernel, this is 5, for processes sm, fs, pm, loader, and pxi."
+     */
+    KERNEL_SPAWNED_PIDS = 26,
+};
+
+/**
+ * Accepted by svcGetSystemInfo param with REGION_MEMORY_USAGE type. Selects a region to query
+ * memory usage of.
+ */
+enum class SystemInfoMemUsageRegion {
+    ALL = 0,
+    APPLICATION = 1,
+    SYSTEM = 2,
+    BASE = 3,
+};
+
 void CallSVC(u32 immediate);
 
 } // namespace