Codegen floating point stores of constants into integer instructions. This

Codegen floating point stores of constants into integer instructions.  This
allows us to compile:

store float 10.0, float* %P

into:
        mov DWORD PTR [%EAX], 1092616192

instead of:

.CPItest_0:                                     # float 0x4024000000000000
.long   1092616192      # float 10
...
        fld DWORD PTR [.CPItest_0]
        fstp DWORD PTR [%EAX]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13409 91177308-0d34-0410-b5e6-96231b3b80d8