mangle names in nimbase.h using cppDefine (#19395) [backport]

mangle names in nimbase.h
fix comments

config/config.nims

@@ -3,6 +3,11 @@
 cppDefine "errno"
 cppDefine "unix"
 
+# mangle the macro names in nimbase.h
+cppDefine "NAN_INFINITY"
+cppDefine "INF"
+cppDefine "NAN"
+
 when defined(nimStrictMode):
   # xxx add more flags here, and use `-d:nimStrictMode` in more contexts in CI.
 

tests/ccgbugs/tmangle.nim

@@ -0,0 +1,16 @@
+block:
+  proc hello() =
+    let NAN_INFINITY = 12
+    doAssert NAN_INFINITY == 12
+    let INF = "2.0"
+    doAssert INF == "2.0"
+    let NAN = 2.3
+    doAssert NAN == 2.3
+
+  hello()
+
+block:
+  proc hello(NAN: float) =
+    doAssert NAN == 2.0
+
+  hello(2.0)