libpldm: Reorganize source and test files

Primarily this is about moving specification-specific files into
'dsp/' (in the "DMTF Standard Publication" sense[1]) subdirectories of
both src/ and tests/.

[1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP4014_2.14.0.pdf

libpldm is a concrete C implementation of the PLDM family of
specifications. This invokes some accidental complexity[2] such as the
msgbuf APIs and other concerns.

[2]: https://en.wikipedia.org/wiki/No_Silver_Bullet

Separate the essential complexity (everything under the dsp/
subdirectories) from the accidental complexity (almost everything else).

While doing so, I took the opportunity to drop the 'libpldm_' prefix
and '_test' suffix from a variety of tests. The 'libpldm_' prefix is a
hangover from the days when libpldm was a subproject of OpenBMC's pldm
repo. The '_test' suffix feels redundant given the parent directory
path.

Note that we maintain separation of the src/ and tests/. The test suite
is implemented in C++ while libpldm's APIs are declared and defined in
C. The ability to chop all the tests and C++ out of the implementation
by ignoring a subtree seems like a desirable property when vendoring the
library into other projects.

Finally, update the x86_64 GCC ABI dump, as rearranging the source
causes a lot of churn in its definitions.

Change-Id: Icffcc6cf48b3101ecd38168827c0a81cffb8f083
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tests/oem/ibm/meson.build b/tests/oem/ibm/meson.build
index 94c2011..389f83b 100644
--- a/tests/oem/ibm/meson.build
+++ b/tests/oem/ibm/meson.build
@@ -1,4 +1,4 @@
 tests += [
-  'oem/ibm/libpldm_fileio_test',
-  'oem/ibm/libpldm_host_test',
+  'oem/ibm/fileio',
+  'oem/ibm/host',
 ]