Copy over ppc clone from musl

lib/std/special/c.zig

@@ -491,6 +491,71 @@ fn clone() callconv(.Naked) void {
                 \\  syscall
             );
         },
+        .powerpc => {
+            // __clone(func, stack, flags, arg, ptid, tls, ctid)
+            //            3,     4,     5,   6,    7,   8,    9
+
+            // syscall(SYS_clone, flags, stack, ptid, tls, ctid)
+            //                 0      3,     4,    5,   6,    7
+            asm volatile (
+                \\# store non-volatile regs r30, r31 on stack in order to put our
+                \\# start func and its arg there
+                \\stwu 30, -16(1)
+                \\stw 31, 4(1)
+                \\
+                \\# save r3 (func) into r30, and r6(arg) into r31
+                \\mr 30, 3
+                \\mr 31, 6
+                \\
+                \\# create initial stack frame for new thread
+                \\clrrwi 4, 4, 4
+                \\li 0, 0
+                \\stwu 0, -16(4)
+                \\
+                \\#move c into first arg
+                \\mr 3, 5
+                \\#mr 4, 4
+                \\mr 5, 7
+                \\mr 6, 8
+                \\mr 7, 9
+                \\
+                \\# move syscall number into r0
+                \\li 0, 120
+                \\
+                \\sc
+                \\
+                \\# check for syscall error
+                \\bns+ 1f # jump to label 1 if no summary overflow.
+                \\#else
+                \\neg 3, 3 #negate the result (errno)
+                \\1:
+                \\# compare sc result with 0
+                \\cmpwi cr7, 3, 0
+                \\
+                \\# if not 0, jump to end
+                \\bne cr7, 2f
+                \\
+                \\#else: we're the child
+                \\#call funcptr: move arg (d) into r3
+                \\mr 3, 31
+                \\#move r30 (funcptr) into CTR reg
+                \\mtctr 30
+                \\# call CTR reg
+                \\bctrl
+                \\# mov SYS_exit into r0 (the exit param is already in r3)
+                \\li 0, 1
+                \\sc
+                \\
+                \\2:
+                \\
+                \\# restore stack
+                \\lwz 30, 0(1)
+                \\lwz 31, 4(1)
+                \\addi 1, 1, 16
+                \\
+                \\blr
+            );
+        },
         .powerpc64, .powerpc64le => {
             // __clone(func, stack, flags, arg, ptid, tls, ctid)
             //            3,     4,     5,   6,    7,   8,    9