Use useful names for Symbol Addr and Names in Linker.c

Replace `char*` and `void*` with `SymbolName` and `SymbolAddr` in
`Linker.c`. Gives some useful information about what the variables are
used for and also normalizes the types used in Mac, Linux and Windows

Test Plan:
./validate on all platforms that use the runtime linker.

For unix platforms please ensure `DYNAMIC_GHC_PROGRAMS=NO` is
 added to your validate file.

This is a continuation from D2184

Reviewers: austin, erikd, simonmar, bgamari

Reviewed By: bgamari

Subscribers: thomie, #ghc_windows_task_force

Differential Revision: https://phabricator.haskell.org/D2250

GHC Trac Issues: #11816

1 files changed, 5 insertions, 2 deletions

diff --git a/rts/RtsSymbols.h b/rts/RtsSymbols.h
index 10c158c027..00ed590514 100644
--- a/rts/RtsSymbols.h
+++ b/rts/RtsSymbols.h
@@ -17,9 +17,12 @@
 #define MAYBE_LEADING_UNDERSCORE_STR(s) (s)
 #endif
 
+typedef char* SymbolName;
+typedef void* SymbolAddr;
+
 typedef struct _RtsSymbolVal {
-    const char   *lbl;
-    void   *addr;
+    const SymbolName lbl;
+    SymbolAddr addr;
 } RtsSymbolVal;