Highlight comments in c, cpp, cmake and llvm (#1309)

Also, reuse the c injections in glsl

runtime/queries/c/injections.scm

@@ -0,0 +1,2 @@
+((comment) @injection.content
+ (#set! injection.language "comment"))

runtime/queries/cmake/injections.scm

@@ -0,0 +1,4 @@
+((line_comment) @injection.content
+ (#set! injection.language "comment"))
+((bracket_comment) @injection.content
+ (#set! injection.language "comment"))

runtime/queries/cpp/injections.scm

@@ -0,0 +1 @@
+; inherits: c

runtime/queries/glsl/injections.scm

@@ -1,5 +1,4 @@
+; inherits: c
+
 ((preproc_arg) @injection.content
  (#set! injection.language "glsl"))
-
-((comment) @injection.content
- (#set! injection.language "comment"))

runtime/queries/llvm/injections.scm

@@ -0,0 +1,2 @@
+((comment) @injection.content
+ (#set! injection.language "comment"))