devel/strace: fix build only on powerpc arch

Reboot of 519a199c
Which broke other builds.

This time, added compile flags to build only for POWERPC archs

Tested on mpc85xx, ar71xx and bcm2708.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

package/devel/strace/patches/100-workaround--pt-reg-collisions-ppc.patch

+diff --git a/ptrace.h b/ptrace.h
+index ddb46cb..48a54b8 100644
+--- a/ptrace.h
++++ b/ptrace.h
+@@ -55,7 +55,14 @@ extern long ptrace(int, int, char *, long);
+ # define ptrace_peeksiginfo_args XXX_ptrace_peeksiginfo_args
+ #endif
+ 
++#if POWERPC
++#include <linux/types.h>
++#define __ASSEMBLY__
++#endif
+ #include <linux/ptrace.h>
++#if POWERPC
++#undef __ASSEMBLY__
++#endif
+ 
+ #ifdef HAVE_STRUCT_IA64_FPREG
+ # undef ia64_fpreg