RFR: JDK-8149647 Incremental enhancements from build-infra

[Magnus Ihse Bursie]

Here is another batch of small fixes and enhancements from the 
build-infra project forest.

* Compiler version framework:
   - Create a TOOLCHAIN_CHECK_COMPILER_VERSION macro
   - Test for minimum versions for certain compilers in configure
* Start supporting mapfiles on all platforms (windows and macosx as well)
* Fix errors/bad looking output in configure
* Fix bugs for debug symbols on macosx when building with 
--with-native-debug-symbols=external
* Simplify hotspot version.rc: replace HS_VER with JDK_VER, and 
HS_DOTVER with JDK_DOTVER (they are always the same)
* INCLUDE_SA fixes:
   - Move the check of INCLUDE_SA to jdk-options.m4.
   - Use INCLUDE_SA for proper testing for SA in makefiles.
* Set --with-native-debug-symbols default to "none" for STATIC_BUILD.
* Compare script improvements
* Incremental fixes in NativeCompilation.gmk.
* Incremental fixes in flags.m4
* Remove left-over comments
* Misc other changes
* Whitespace fixes

Bug: https://bugs.openjdk.java.net/browse/JDK-8149647
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8149647-incremental-build-infra-fixes-incl-compiler-version/webrev.01

/Magnus