Fix -Wconversion warnings in runtime, oops and some code header files.

Several header files have size calculations like size = address - address in same blob, that require casting to int.

Changed type of GrowableArray<> for bcis and jsrs in GenerateOopMap.

Changed type of 'phase' to char in jvmFlags.

Eliminating this many warnings (multiplied because of header file inclusions):

2439 src/hotspot/share/code/codeBlob.hpp
830 src/hotspot/share/oops/methodCounters.hpp
693 src/hotspot/share/runtime/stubCodeGenerator.hpp
657 src/hotspot/cpu/x86/nativeInst_x86.hpp
617 src/hotspot/share/oops/compressedOops.inline.hpp
614 src/hotspot/share/oops/stackChunkOop.inline.hpp
614 src/hotspot/share/code/codeBlob.inline.hpp
614 src/hotspot/cpu/x86/frame_x86.inline.hpp
591 src/hotspot/share/ci/ciStreams.hpp
245 src/hotspot/share/code/exceptionHandlerTable.hpp
243 src/hotspot/share/code/dependencies.hpp
170 src/hotspot/share/services/mallocHeader.hpp
94 src/hotspot/share/ci/ciMethodData.hpp
86 src/hotspot/share/utilities/nativeCallStack.hpp
85 src/hotspot/share/services/mallocSiteTable.hpp
72 src/hotspot/share/c1/c1_Instruction.hpp
42 src/hotspot/share/code/vtableStubs.hpp
25 src/hotspot/share/utilities/globalDefinitions.hpp
25 src/hotspot/share/runtime/flags/jvmFlagLimit.hpp
22 src/hotspot/share/classfile/classFileStream.hpp
21 src/hotspot/share/oops/generateOopMap.hpp
18 src/hotspot/share/c1/c1_CodeStubs.hpp
18 src/hotspot/os/linux/cgroupSubsystem_linux.hpp
14 src/hotspot/share/utilities/align.hpp
9 src/hotspot/share/utilities/elfFile.hpp
8 src/hotspot/share/cds/archiveHeapWriter.hpp
7 src/hotspot/share/oops/generateOopMap.cpp
4 src/hotspot/share/utilities/powerOfTwo.hpp
4 src/hotspot/share/runtime/continuationHelper.inline.hpp
2 src/hotspot/share/prims/jvmtiTagMapTable.hpp
2 src/hotspot/cpu/x86/stackChunkFrameStream_x86.inline.hpp
1 src/hotspot/cpu/x86/continuationFreezeThaw_x86.inline.hpp