riscv: Use __riscv_flush_icache() on Linux.

This seems to perhaps clear icache on all harts.  Otherwise crashing is
seen.  Not sure what to do on other platforms.

Common/RiscVEmitter.cpp

@@ -18,6 +18,9 @@
 #include "ppsspp_config.h"
 #include <algorithm>
 #include <cstring>
+#if PPSSPP_ARCH(RISCV64) && PPSSPP_PLATFORM(LINUX)
+#include <sys/cachectl.h>
+#endif
 #include "Common/BitScan.h"
 #include "Common/CPUDetect.h"
 #include "Common/RiscVEmitter.h"
@@ -1051,8 +1054,13 @@ void RiscVEmitter::FlushIcache() {
 
 void RiscVEmitter::FlushIcacheSection(const u8 *start, const u8 *end) {
 #if PPSSPP_ARCH(RISCV64)
+#if PPSSPP_PLATFORM(LINUX)
+	__riscv_flush_icache((char *)start, (char *)end, 0);
+#else
+	// TODO: This might only correspond to a local hart icache clear, which is no good.
 	__builtin___clear_cache((char *)start, (char *)end);
 #endif
+#endif
 }
 
 FixupBranch::~FixupBranch() {