binfmt-detector-cli: rewrite to support PE32+ binaries (#38)

Rewrite with hard-coded offsets into the PE file format to discern
if a binary is PE32 or PE32+, and then to determine if it contains
a "CLR Data Directory" entry that looks valid.

Tested with PE32 and PE32+ compiled Mono binaries, PE32 and PE32+ native
binaries, and a random assortment of garbage files.

Former-commit-id: 9e7ac86ec84f653a2f79b87183efd5b0ebda001b

mcs/class/System.Web/Test/System.Web.UI.WebControls/DetailsViewTest.cs.REMOVED.git-id

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-12a7ab9e97bc4ad43efdca1e7f12435ee44c417c

mcs/class/System.Web/Test/System.Web.UI.WebControls/GridViewTest.cs.REMOVED.git-id

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-7561fd84425b70a803d0918521917d5d9deb3e8c

mcs/class/System.Web/Test/System.Web.UI.WebControls/RepeatInfoTest.auto.4.0.cs.REMOVED.git-id

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-64aa7ad1b5a33e952dcb1afafb94208f77a1a2e8

mcs/class/System.Web/Test/System.Web.UI.WebControls/TreeViewTest.cs.REMOVED.git-id

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-26c5088ccf80d21e12be7aaaee864949746300b3