Add Bazel support #211

Job	Run time
windows (Win32, standard)	1m 33s
ubuntu (g++, standard)	57s
windows (Win32, PUGIXML_WCHAR_MODE)	56s
ubuntu (g++, PUGIXML_WCHAR_MODE)	1m 1s
windows (Win32, PUGIXML_COMPACT)	1m 25s
ubuntu (g++, PUGIXML_COMPACT)	57s
windows (Win32, PUGIXML_NO_EXCEPTIONS)	1m 50s
ubuntu (g++, PUGIXML_NO_EXCEPTIONS)	52s
windows (x64, standard)	1m 24s
ubuntu (clang++, standard)	37s
windows (x64, PUGIXML_WCHAR_MODE)	1m 33s
ubuntu (clang++, PUGIXML_WCHAR_MODE)	39s
windows (x64, PUGIXML_COMPACT)	1m 44s
ubuntu (clang++, PUGIXML_COMPACT)	41s
windows (x64, PUGIXML_NO_EXCEPTIONS)	1m 41s
ubuntu (clang++, PUGIXML_NO_EXCEPTIONS)	36s
macos (clang++, standard)	1m 16s
macos (clang++, PUGIXML_WCHAR_MODE)	3m 37s
macos (clang++, PUGIXML_COMPACT)	3m 21s
macos (clang++, PUGIXML_NO_EXCEPTIONS)	1m 12s
	27m 52s

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