build: fix coverage build

After adding the node_lib target in node.gyp, most of the node source
files are moved to that target. When coverage option is enabled,
corresponding cflags and ldflags are needed in that target as well.
gcovr also needs to check .gcda data for both node and node_lib.

Fixes: #18402

Signed-off-by: Yihong Wang <yh.wang@ibm.com>

Makefile

@@ -191,6 +191,9 @@ coverage-test: coverage-build
 	$(RM) out/$(BUILDTYPE)/obj.target/node/gen/*.gcda
 	$(RM) out/$(BUILDTYPE)/obj.target/node/src/*.gcda
 	$(RM) out/$(BUILDTYPE)/obj.target/node/src/tracing/*.gcda
+	$(RM) out/$(BUILDTYPE)/obj.target/node_lib/gen/*.gcda
+	$(RM) out/$(BUILDTYPE)/obj.target/node_lib/src/*.gcda
+	$(RM) out/$(BUILDTYPE)/obj.target/node_lib/src/tracing/*.gcda
 	-$(MAKE) $(COVTESTS)
 	mv lib lib__
 	mv lib_ lib
@@ -201,7 +204,7 @@ coverage-test: coverage-build
 		--temp-directory "$(CURDIR)/.cov_tmp" \
 		--report-dir "../coverage")
 	-(cd out && "../gcovr/scripts/gcovr" --gcov-exclude='.*deps' \
-		--gcov-exclude='.*usr' -v -r Release/obj.target/node \
+		--gcov-exclude='.*usr' -v -r Release/obj.target \
 		--html --html-detail -o ../coverage/cxxcoverage.html \
 		--gcov-executable="$(GCOV)")
 	mv lib lib_

node.gypi

@@ -184,25 +184,20 @@
       ],
     }],
     [ '(OS=="freebsd" or OS=="linux") and node_shared=="false"'
-        ' and coverage=="false" and force_load=="true"', {
+        ' and force_load=="true"', {
       'ldflags': [ '-Wl,-z,noexecstack',
                    '-Wl,--whole-archive <(v8_base)',
                    '-Wl,--no-whole-archive' ]
     }],
-    [ '(OS=="freebsd" or OS=="linux") and node_shared=="false"'
-        ' and coverage=="true" and force_load=="true"', {
-      'ldflags': [ '-Wl,-z,noexecstack',
-                   '-Wl,--whole-archive <(v8_base)',
-                   '-Wl,--no-whole-archive',
-                   '--coverage',
+    [ 'OS in "mac freebsd linux" and node_shared=="false"'
+        ' and coverage=="true"', {
+      'ldflags': [ '--coverage',
                    '-g',
                    '-O0' ],
-       'cflags': [ '--coverage',
+      'cflags': [ '--coverage',
                    '-g',
                    '-O0' ],
-       'cflags!': [ '-O3' ]
-    }],
-    [ 'OS=="mac" and node_shared=="false" and coverage=="true"', {
+      'cflags!': [ '-O3' ],
       'xcode_settings': {
         'OTHER_LDFLAGS': [
           '--coverage',