Preprocessor directives can now appear in the argument list of function-like macro calls.

#pragma PP-tokens can now be macro replaced.
#include header names directly enclosed in <> are free of macro replacement.
Preprocess-only mode (-E) now outputs with #line as source info.
Moved testcases for #760 and #1357.
Added testcase for #1643.

test/val/bug1643.c

@@ -0,0 +1,12 @@
+/* bug #1643, macro expansion in #include */
+
+#define MKSTR(a)        MKSTR_IMPL(a)
+#define MKSTR_IMPL(a)   #a
+#define BUG1643_H       bug1643.h
+
+#include MKSTR(BUG1643_H)
+
+int main(void)
+{
+    return BUG1643_RESULT;
+}