Adding CMake support for Windows, Mac, Linux and Android Co-Authored-By: evpobr

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>
diff --git a/opus_sources.mk b/opus_sources.mk
index b0763f9..44153b5 100644
--- a/opus_sources.mk
+++ b/opus_sources.mk
@@ -1,4 +1,5 @@
-OPUS_SOURCES = src/opus.c \
+OPUS_SOURCES = \
+src/opus.c \
 src/opus_decoder.c \
 src/opus_encoder.c \
 src/opus_multistream.c \