fix defect7654 that  the encoder won't generate IDR when temporal layer setting changes
Inject STL_INCLUDES via MODULE_INCLUDES for the gmp plugin

This avoids having to rely on manual modifications to targets.mk,
which are overwritten if the targets.mk files are regenerated
via the script.
add IDR processing in gmp wrapper
Make sure that libgmpopenh264.so is removed on "make clean"

Nothing used the makefile variable $(PLUGINS), and $(LIBRARIES)
is only used for the clean target.
Use a less generic name for linking to STL when building the plugin for android

This matches the common naming scheme more closely for adding extra
flags to individual parts of the build.

Also deduplicate the static stlport lib name.
Don't build an unused libmodule.a file

This also avoids another manual edit in module/targets.mk. Now
the file is completely autogenerated by the build/mktargets.sh
script, just as all the other targets.mk files.
Print an intX_t by casting to int64_t

The internal intX_t is either int32_t or int64_t depending on
platform bitness. Since there is no existing printf format for
such an integer, cast it to an int64_t and use the right
printf format for that instead.

This avoids warnings when building with clang.
Remove an unused variable

This fixes build warnings when building for OS X with clang.
Merge pull request #1009 from mstorsjo/remove-unused-var

Remove an unused variable
Merge pull request #1010 from mstorsjo/fix-log-format

Print an intX_t by casting to int64_t
Add the external directory gmp-api to gitignore
remove redundant code
format update
Merge pull request #1007 from ruil2/gmp_idr

add IDR processing in gmp wrapper
add iSubSeqId calculation
Merge pull request #1011 from mstorsjo/ignore-gmp

Add the external directory gmp-api to gitignore
format update
Merge pull request #1013 from ruil2/command_db

add iSubSeqId calculation
Merge pull request #1006 from ruil2/bug_fix

    fix defect7654 that  the encoder won't generate IDR when temporal layer setting changes
Merge pull request #1008 from mstorsjo/plugin-build

Clean up minor aspects of the plugin build process