Merge #14281: lcov: filter /usr/lib/ from coverage reports

fa6b30c40b lcov: filter /usr/lib/ from coverage reports (MarcoFalke)

Pull request description:

  This folder was included for me on ubuntu trusty and bionic when creating coverage reports.

  Can be tested by passing `--enable-lcov` +optional `--enable-lcov-branch-coverage` to `./configure`

  Then `make -j 4 && make cov`, which will generate the report in html.

  See https://github.com/bitcoin/bitcoin/blob/master/doc/developer-notes.md#compiling-for-test-coverage

Tree-SHA512: 722deda8bca0d6d63e10dd55848ab72318d5cdbd56ab7ea19a1d1ca7285989bd3f0ccc72c3001aad326e1ce5b008e0a183bb5f05f2225d80ec68377c9434293a

Makefile.am

@@ -168,7 +168,7 @@ $(BITCOIN_CLI_BIN): FORCE
 	$(MAKE) -C src $(@F)
 
 if USE_LCOV
-LCOV_FILTER_PATTERN=-p "/usr/include/" -p "src/leveldb/" -p "src/bench/" -p "src/univalue" -p "src/crypto/ctaes" -p "src/secp256k1"
+LCOV_FILTER_PATTERN=-p "/usr/include/" -p "/usr/lib/" -p "src/leveldb/" -p "src/bench/" -p "src/univalue" -p "src/crypto/ctaes" -p "src/secp256k1"
 
 baseline.info:
 	$(LCOV) -c -i -d $(abs_builddir)/src -o $@