FTBFS with -O3 on ppc64el

[Logan Rosen]

w1retap FTBFS with -O3 on ppc64el: https://launchpad.net/ubuntu/+source/w1retap/1.4.4-4ubuntu1/+build/20784039

I've uploaded a version that uses -O2 instead, but we should look into why there's a failure with -O3 so that we can avoid that workaround.

Relevant log snippet:

gcc -DHAVE_CONFIG_H -I. -I../.. -Wall -D_GNU_SOURCE=1 -I . -pthread -I/usr/include/glib-2.0 -I/usr/lib/powerpc64le-linux-gnu/glib-2.0/include -Wdate-time -D_FORTIFY_SOURCE=2 -Werror -Wno-unused-result -g -O3 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wall -c -o owprgm.o owprgm.c
gcc -DHAVE_CONFIG_H -I. -I../.. -Wall -D_GNU_SOURCE=1 -I . -pthread -I/usr/include/glib-2.0 -I/usr/lib/powerpc64le-linux-gnu/glib-2.0/include -Wdate-time -D_FORTIFY_SOURCE=2 -Werror -Wno-unused-result -g -O3 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wall -c -o owcache.o owcache.c
gcc -DHAVE_CONFIG_H -I. -I../.. -Wall -D_GNU_SOURCE=1 -I . -pthread -I/usr/include/glib-2.0 -I/usr/lib/powerpc64le-linux-gnu/glib-2.0/include -Wdate-time -D_FORTIFY_SOURCE=2 -Werror -Wno-unused-result -g -O3 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wall -c -o temp10.o temp10.c
owprgm.c: In function ‘setJobData’:
owprgm.c:816:28: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
  816 | job.Page[pg].data[i] = buff[i];
      | ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
In file included from owprgm.c:33:
owfile.h:115:17: note: at offset [29, 30] to object ‘data’ with size 29 declared here
  115 | uchar data[29]; // data to write
      | ^~~~
owprgm.c:816:28: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
  816 | job.Page[pg].data[i] = buff[i];
      | ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
In file included from owprgm.c:33:
owfile.h:115:17: note: at offset 30 to object ‘data’ with size 29 declared here
  115 | uchar data[29]; // data to write
      | ^~~~
owfile.c: In function ‘owOpenFile’:
owfile.c:1271:16: note: the layout of aggregates containing vectors with 1-byte alignment has changed in GCC 5
 1271 | Han[hn].Ext = flname->Ext & 0x7F;
      | ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
gcc -DHAVE_CONFIG_H -I. -I../.. -Wall -D_GNU_SOURCE=1 -I . -pthread -I/usr/include/glib-2.0 -I/usr/lib/powerpc64le-linux-gnu/glib-2.0/include -Wdate-time -D_FORTIFY_SOURCE=2 -Werror -Wno-unused-result -g -O3 -fdebug-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat -Werror=format-security -Wall -c -o atod26.o atod26.c
cc1: all warnings being treated as errors
make[5]: *** [Makefile:926: owprgm.o] Error 1