[NFC] fix trivial typos in comments and documents
"in in" -> "in", "on on" -> "on" etc.
#
# Run as: CLANG=bin/clang ZLIB_SRC=src/zlib \
# build_symbolizer.sh runtime_build/lib/clang/4.0.0/lib/linux/
-# zlib can be downloaded from from http://www.zlib.net.
+# zlib can be downloaded from http://www.zlib.net.
#
# Script compiles self-contained object file with symbolization code and injects
# it into the given set of runtime libraries. Script updates only libraries
