Include Git revision in version info.

CMakeLists.txt contains now the version numbers for DMD and (next) LDC release.
If a .git folder is found then the LDC version is replaced by the first 6 chars
of the Git revision.

Possible improvements:

- If the build is not done at the master branch then it could be useful to check for a tag and use the tag instead of the revision. (for release builds)
- Maybe it is useful to include the branch name.

This fixes issue #366.

dmd2/mars.c

@@ -103,9 +103,6 @@ void Global::init()
     compiler.vendor = "Digital Mars D";
 #endif
 #if IN_LLVM
-    version = "v2.063";
-    ldc_version = "trunk";
-    llvm_version = "LLVM " LDC_LLVM_VERSION_STRING;
     compiler.vendor = "LDC";
 #endif
 

dmd2/mars.h

@@ -341,8 +341,8 @@ struct Global
 
     const char *version;
 #if IN_LLVM
-    char *ldc_version;
-    char *llvm_version;
+    const char *ldc_version;
+    const char *llvm_version;
 
     bool inExtraInliningSemantic;
 #endif