Add gitattributes.

Author: utkarshayachit

.gitattributes

@@ -0,0 +1,20 @@
+.git*            export-ignore
+.hooks*          export-ignore
+
+*.sh             crlf=input
+*.sh.in          crlf=input
+
+# Custom attribute to mark sources as using our C code style.
+[attr]our-c-style  whitespace=tab-in-indent,-blank-at-eol  format.clang-format
+
+*.c              our-c-style
+*.h              our-c-style
+*.cpp            our-c-style
+*.cxx            our-c-style
+*.hxx            our-c-style
+*.txx            our-c-style
+*.mm             our-c-style
+*.txt            whitespace=tab-in-indent,-blank-at-eol
+*.cmake          whitespace=tab-in-indent,-blank-at-eol
+
+*.md             whitespace=tab-in-indent conflict-marker-size=30