Fix building error with '-O2' in sysroot path

* cipher/Makefile.am (o_flag_munging): Tweak the sed script.
* random/Makefile.am (o_flag_munging): Ditto.

Characters like '-O2' or '-Ofast' will be replaced by '-O1' and '-O0'
respectively when compiling cipher and random in the filesystem
paths as well if they happen to contain '-O2' or '-Ofast

If we are cross compiling libgcrypt and sysroot contains such
characters, we would
get compile errors because the sysroot path has been modified.

Fix this by adding blank spaces and tabs before the original matching
pattern in the sed command.

ChangeLog entries added by wk

Note that there is also the configure option --disable-O-flag-munging;
see the README.

• Signed-off-by: simit.ghane <simit.ghane@lge.com>