Update test output to work with HTSlib Number= PR htslib#1874

htslib#1874 changes `bcf_remove_allele_set()` so that it no longer
removes format fields with Type=String, Number=G and the only
value left is MISSING.  This alters the output of a couple of the
`bcftools view -a` tests as the `FGS` tag is kept with a MISSING
value instead of being removed completely.

Author: daviesrob

test/view.vectors.C.out

@@ -25,4 +25,4 @@
 #CHROM	POS	ID	REF	ALT	QUAL	FILTER	INFO	FORMAT	A
 1	10	.	A	C	999	PASS	IAF=.;IRF=.;IGF=.;IAI=.;IRI=.;IGI=.;IAS=.;IRS=.,.;IGS=.,.,.;AC=1;AN=2	GT:FAF:FRF:FGF:FAI:FRI:FGI:FAS:FRS:FGS	0/1:.:.:.:.:.:.:.:.,.:.,.,.
 1	20	.	A	T	999	PASS	IAF=.;IRF=.;IGF=.;IAI=.;IRI=.;IGI=.;IAS=.;IRS=.,.;IGS=.,.,.;AC=1;AN=2	GT:FAF:FRF:FGF:FAI:FRI:FGI:FAS:FRS:FGS	0/1:.:.:.:.:.:.:.:.:.
-1	30	.	G	A	999	PASS	IAF=.;IRF=.;IGF=.;IAI=.;IRI=.;IGI=.;IAS=.;IRS=.;IGS=.;AC=1;AN=2	GT:FAF:FRF:FGF:FAI:FRI:FGI:FAS:FRS	0/1:.:.:.:.:.:.:.:.
+1	30	.	G	A	999	PASS	IAF=.;IRF=.;IGF=.;IAI=.;IRI=.;IGI=.;IAS=.;IRS=.;IGS=.;AC=1;AN=2	GT:FAF:FRF:FGF:FAI:FRI:FGI:FAS:FRS:FGS	0/1:.:.:.:.:.:.:.:.:.