Android: Add chrome-specific dynamic linker.

base/android/linker/crazy_linker/README.TXT

Index: base/android/linker/crazy_linker/README.TXT
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+A custom dynamic linker for Android programs that adds a few interesting
+features compared to /system/bin/linker:
+
+  - Supports loading a library at an explicit (page-aligned) memory
+    address. The system linker always randomizes the address.
+
+  - Supports loading a library from an explicit (page-aligned) file
+    offset. This can be useful to load a library directly from an .apk,
+    provided that it is uncompressed and at a page-aligned offset.
+
+  - Support changing the library search path. The system linker, when used
+    inside Android applications, is limited to the boot LD_LIBRARY_PATH
+    value, that only looks into system directories, not application ones.
+
+  - Support sharing of RELRO sections. When two processes load the same
+    library at exactly the same address, the content of its RELRO section
+    is identical. By default, each instance uses private RAM pages to host
+    it, but it is possible to use a single ashmem region to share the same
+    data instead.
+
+See include/crazy_linker.h for the API and its documentation.
+
+A few notes:
+
+  - The crazy linker will always use the system linker to load system
+    libraries (e.g. liblog.so and others). This avoids having two instances
+    of the same library in the same process, and correctly resolving any
+    symbols from system libraries.
+
+  - Any library loaded by the crazy linker, and which uses functions of
+    libdl.so will continue to work. However, calls to dlopen(), dlsym(),
+    et al will be redirected to the crazy linker's own wrappers.
+
+    This ensures that if a library is loaded by the crazy linker, any of
+    its dependencies will be loaded by it too.
+
+BUGS & TODO:
+  - At the moment, libraries loaded by the crazy linker are not visible
+    by GDB or third-party tools like Breakpad. Similarly, cross-library
+    stack unwinding has not been tested yet.
+
+  - Libraries loaded by the crazy linker are not automatically closed when
+    the process exits.