Extend the syntax of #line and __FILE__ to support filename strings.

According to the GLSL spec, the second parameter to #line should be
an integer source string number and __FILE__ will be substituted
with the integer source string number currently processed. This
patch extends the syntax of #line and __FILE__. Now #line accepts
as the second parameter a filename string quoted by double quotation
marks. And if such a #line is set, __FILE__ will be substituted with
the currently set filename string. The implementation is done via
introducing a new extension GL_GOOGLE_cpp_style_line_directive using
the extension framework.

The purpose is to support cpp-style #line directives, which is
required by #include.

Test/baseResults/preprocessor.cpp_style___FILE__.vert.out

@@ -0,0 +1,26 @@
+#extension GL_GOOGLE_cpp_style_line_directive : enable
+
+0
+#line 150 a.h
+ "a.h"
+#line 24
+ "a.h"
+#line 42
+ "a.h"
+#line 30 b.cc
+ "b.cc"
+#line 10 3
+ 3
+#line 48
+ 3
+#line 4
+ 3
+#line 55 100
+ 100
+#line 1000 c
+ "c"
+#line 42 1
+ 1
+#line 42 this-is-a-quite-long-name-maybe-i-should-shorten-it
+ "this-is-a-quite-long-name-maybe-i-should-shorten-it"
+

Test/baseResults/preprocessor.cpp_style_line_directive.vert.err

@@ -0,0 +1,15 @@
+ERROR: 0:3: '#error' : at 0:3
+ERROR: a.h:150: '#error' : at a.h:150
+ERROR: a.h:24: '#error' : at a.h:24
+ERROR: a.h:42: '#error' : at a.h:42
+ERROR: b.cc:30: '#error' : at b.cc:30
+ERROR: 3:10: '#error' : at 3:10
+ERROR: 3:48: '#error' : at 3:48
+ERROR: 3:4: '#error' : at 3:4
+ERROR: 100:55: '#error' : at 100:55
+ERROR: c:1000: '#error' : at c:1000
+ERROR: 1:42: '#error' : at 1:42
+ERROR: this-is-a-quite-long-name-maybe-i-should-shorten-it:42: '#error' : at this-is-a-quite-long-name-maybe-i-should-shorten-it:42
+ERROR: 12 compilation errors.  No code generated.
+
+