net/mosh: fix build on powerpc*

ocb_internal.cc:138:10: warning: 'bswap32' macro redefined [-Wmacro-redefined]
        #define bswap32(x)                                              \
                ^
/usr/include/sys/endian.h:68:9: note: previous definition is here
        ^
ocb_internal.cc:142:26: error: static declaration of '__builtin_bswap64' follows non-static declaration
         static inline uint64_t bswap64(uint64_t x) {
                                ^
/usr/include/sys/endian.h:69:20: note: expanded from macro 'bswap64'
                        ^
/usr/include/sys/_endian.h:78:22: note: expanded from macro '__bswap64'
                        ^
ocb_internal.cc:142:26: note: previous implicit declaration is here
/usr/include/sys/endian.h:69:20: note: expanded from macro 'bswap64'
                        ^
/usr/include/sys/_endian.h:78:22: note: expanded from macro '__bswap64'
                        ^
1 warning and 1 error generated.

net/mosh/Makefile

@@ -15,7 +15,7 @@ USE_PERL5=	run
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS=	--with-utempter --without-ncurses
 CONFIGURE_ENV+=	OpenSSL_CFLAGS="-I${OPENSSLINC}" OpenSSL_LIBS="-L${OPENSSLLIB} -lssl -lcrypto" \
-		TINFO_CFLAGS="-I/usr/include"
+		TINFO_CFLAGS="-I/usr/include" ac_cv_have_decl_bswap64=yes
 INSTALL_TARGET=	install-strip
 USE_CXXSTD=	c++11