build-sys: Fix a couple of meson warnings

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/556>

doxygen/doxygen.conf.in

@@ -758,8 +758,8 @@ EXCLUDE_SYMBOLS        =
 # directories that contain example code fragments that are included (see
 # the \include command).
 
-EXAMPLE_PATH           = @srcdir@/../src/utils \
-                         @srcdir@/../src/tests
+EXAMPLE_PATH           = @top_srcdir@/src/utils \
+                         @top_srcdir@/src/tests
 
 # If the value of the EXAMPLE_PATH tag contains directories, you can use the
 # EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp

meson.build

@@ -164,6 +164,7 @@ cdata.set('top_srcdir', meson.source_root())
 # First some defaults to keep config file generation happy
 cdata.set('HAVE_COREAUDIO', 0)
 cdata.set('HAVE_WAVEOUT', 0)
+cdata.set('OS_IS_FREEBSD', 0)
 
 platform_socket_dep = []
 platform_dep = []