tests: Fix LCOV_OPTS to be in the correct position

`lcov`'s `-a` option takes an argument. With `LCOV_OPTS` immediately
after `-a`, the first additional argument becomes the argument to `-a`
which is incorrect.

Also add `LCOV_OPTS` to more `lcov` calls.

Makefile.am

@@ -189,7 +189,7 @@ $(COV_TOOL_WRAPPER):
 	@chmod +x $(COV_TOOL_WRAPPER)
 
 baseline.info: $(COV_TOOL_WRAPPER)
-	$(LCOV) -c -i -d $(abs_builddir)/src -o $@
+	$(LCOV) $(LCOV_OPTS) -c -i -d $(abs_builddir)/src -o $@
 
 baseline_filtered.info: baseline.info
 	$(abs_builddir)/contrib/filter-lcov.py $(LCOV_FILTER_PATTERN) $< $@
@@ -223,13 +223,13 @@ functional_test_filtered.info: functional_test.info
 	$(LCOV) -a $@ $(LCOV_OPTS) -o $@
 
 fuzz_coverage.info: fuzz_filtered.info
-	$(LCOV) -a $(LCOV_OPTS) baseline_filtered.info -a fuzz_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
+	$(LCOV) $(LCOV_OPTS) -a baseline_filtered.info -a fuzz_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
 
 test_bitcoin_coverage.info: baseline_filtered.info test_bitcoin_filtered.info
-	$(LCOV) -a $(LCOV_OPTS) baseline_filtered.info -a test_bitcoin_filtered.info -o $@
+	$(LCOV) $(LCOV_OPTS) -a baseline_filtered.info -a test_bitcoin_filtered.info -o $@
 
 total_coverage.info: test_bitcoin_filtered.info functional_test_filtered.info
-	$(LCOV) -a $(LCOV_OPTS) baseline_filtered.info -a test_bitcoin_filtered.info -a functional_test_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
+	$(LCOV) $(LCOV_OPTS) -a baseline_filtered.info -a test_bitcoin_filtered.info -a functional_test_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
 
 fuzz.coverage/.dirstamp: fuzz_coverage.info
 	$(GENHTML) -s $(LCOV_OPTS) $< -o $(@D)