fix pread/pwrite syscall calling convention on sh

despite sh not generally using register-pair alignment for 64-bit
syscall arguments, there are arch-specific versions of the syscall
entry points for pread and pwrite which include a dummy argument for
alignment before the 64-bit offset argument.

arch/sh/syscall_arch.h

@@ -2,6 +2,7 @@
 ((union { long long ll; long l[2]; }){ .ll = x }).l[0], \
 ((union { long long ll; long l[2]; }){ .ll = x }).l[1]
 #define __SYSCALL_LL_O(x) __SYSCALL_LL_E((x))
+#define __SYSCALL_LL_PRW(x) 0, __SYSCALL_LL_E((x))
 
 /* The extra OR instructions are to work around a hardware bug:
  * http://documentation.renesas.com/doc/products/mpumcu/tu/tnsh7456ae.pdf

src/internal/syscall.h

@@ -12,6 +12,10 @@
 #define SYSCALL_MMAP2_UNIT 4096ULL
 #endif
 
+#ifndef __SYSCALL_LL_PRW
+#define __SYSCALL_LL_PRW(x) __SYSCALL_LL_O(x)
+#endif
+
 #ifndef __scc
 #define __scc(X) ((long) (X))
 typedef long syscall_arg_t;

src/unistd/pread.c

@@ -4,7 +4,7 @@
 
 ssize_t pread(int fd, void *buf, size_t size, off_t ofs)
 {
-	return syscall_cp(SYS_pread, fd, buf, size, __SYSCALL_LL_O(ofs));
+	return syscall_cp(SYS_pread, fd, buf, size, __SYSCALL_LL_PRW(ofs));
 }
 
 LFS64(pread);

src/unistd/pwrite.c

@@ -4,7 +4,7 @@
 
 ssize_t pwrite(int fd, const void *buf, size_t size, off_t ofs)
 {
-	return syscall_cp(SYS_pwrite, fd, buf, size, __SYSCALL_LL_O(ofs));
+	return syscall_cp(SYS_pwrite, fd, buf, size, __SYSCALL_LL_PRW(ofs));
 }
 
 LFS64(pwrite);