util/uri.c: wrap single statement blocks with braces {}

util/uri.c: wrap single statement blocks with braces {}

For this patch, using curly braces to wrap `if` `while` `else` statements,
which only hold single statement. For example:
'''
if (cond)
    statement;
'''
to
'''
if (cond) {
    statement;
}
'''

And using tricks that compare the disassemblies before and after
code changes, to make sure code logic isn't changed:
'''
git checkout master
make util/uri.o
strip util/uri.o
objdump -Drx util/uri.o > /tmp/uri-master.txt
git checkout cleanupbranch
make util/uri.o
strip util/uri.o
objdump -Drx util/uri.o > /tmp/uri-cleanup.txt

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>