Add CMake build script

Description
===========

This patch adds support of CMake meta build system, so you can generate
Unix makefiles, VS 6.0-2017 projects and many more.

Features
========

* Win32 and Linux tested
* Travis CI test added
* Generates working Visual Studio 6.0-2017 solutions
* Generates working Unix Makefile
* Supported options (<option> - <default value>):
  * `ENABLE_FLOATING_POINT` - on
  * `ENABLE_FIXED_POINT` - off
  * `ENABLE_FIXED_POINT_DEBUG` - off
  * `USE_GPL_FFTW3` - off
  * `DISABLE_FLOAT_API` - off
  * `DISABLE_VBR` - off
  * `ENABLE_VORBIS_PSY` - off
  * `ENABLE_SSE` - on if supported
  * `ENABLE_ARM4_ASM` - off
  * `ENABLE_ARM5E_ASM` - off
  * `ENABLE_BLACKFIN_ASM` - off
  * `ENABLE_TI_C55X` - off
  * `USE_SPEEXDSP` - on if library found
  * `DISABLE_BINARIES` - off
  * `ENABLE_PACKAGE_CONFIG` - on, [CMake specific](https://cmake.org/cmake/help/latest/manual/cmake-packages.7.html#package-configuration-file)
* Configured conditionals (`config.h`):
  * `WORDS_BIGENDIAN`
  * `FLOATING_POINT`
  * `FIXED_POINT`
  * `FIXED_POINT_DEBUG`
  * `DISABLE_FLOAT_API`
  * `_USE_SSE`
  * `ARM4_ASM`
  * `ARM5E_ASM`
  * `BFIN_ASM`
  * `TI_C55X`
  * `DISABLE_VBR`
  * `USE_SPEEXDSP`
  * `VORBIS_PSYCHO`
  * `HAVE_GETOPT_H`
  * `HAVE_GETOPT_LONG`
  * `VAR_ARRAYS`
  * `USE_ALLOCA`
  * `HAVE_ALLOCA_H`
  * `USE_SMALLFT`
  * `USE_KISS_FFT`
  * `USE_GPL_FFTW3`
  * `EXPORT`
* Installation supported
* Package config mode supported

How to use
==========

Required tools and libraries:

* CMake >= 3.1
* Ogg, SpeexDSP packages (headers and import libraries), recommended
* FFTW3 package, optional

Type commands:

```
mkdir cmake-build
cd cmake-build
cmake ..
cmake . --build
```

or use CMake GUI.

.gitignore

@@ -43,3 +43,13 @@ src/speexdec
 src/speexenc
 stamp-*
 patches
+
+CMakeCache.txt
+CMakeFiles
+CMakeScripts
+Testing
+Makefile
+cmake_install.cmake
+install_manifest.txt
+compile_commands.json
+CTestTestfile.cmake

.travis.yml

@@ -1,11 +1,25 @@
 language: c
+sudo: false
+dist: trusty
+addons:
+  apt:
+    packages:
+      - libogg-dev
+      - libspeexdsp-dev
+      - libfftw3-dev
 
 env:
-  - CONFIG=""
-  - CONFIG="--enable-fixed-point"
-  - CONFIG="--enable-fixed-point --disable-float-api"
-  - CONFIG="--enable-vorbis-psy"
-  - CONFIG="--disable-binaries"
+  matrix:
+    - CMAKE=1 CONFIG=""
+    - CMAKE=1 CONFIG="-DENABLE_FIXED_POINT:BOOL=TRUE -DENABLE_FLOATING_POINT:BOOL=FALSE"
+    - CMAKE=1 CONFIG="-DENABLE_FIXED_POINT:BOOL=TRUE -DENABLE_FLOATING_POINT:BOOL=FALSE -DDISABLE_FLOAT_API:BOOL=TRUE"
+    - CMAKE=1 CONFIG="-DENABLE_VORBIS_PSY:BOOL=TRUE"
+    - CMAKE=1 CONFIG="-DDISABLE_BINARIES:BOOL=TRUE"
+    - AUTOTOOLS=1 CONFIG=""
+    - AUTOTOOLS=1 CONFIG="--enable-fixed-point"
+    - AUTOTOOLS=1 CONFIG="--enable-fixed-point --disable-float-api"
+    - AUTOTOOLS=1 CONFIG="--enable-vorbis-psy"
+    - AUTOTOOLS=1 CONFIG="--disable-binaries"
 
 os:
   - linux
@@ -15,7 +29,11 @@ compiler:
   - gcc
   - clang
 
+before_install:
+  - if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
+      brew install libogg speexdsp fftw;
+    fi
+
 script:
-  - ./autogen.sh
-  - ./configure $CONFIG
-  - make distcheck
+  - if [ "$CMAKE" == "1" ]; then mkdir cmake-build; cd cmake-build; cmake .. $CONFIG -DBUILD_SHARED_LIBS:BOOL=TRUE -DCMAKE_INSTALL_PREFIX:PATH=$HOME/cmake-check; make install; fi
+  - if [ "$AUTOTOOLS" == "1" ]; then ./autogen.sh; ./configure $CONFIG; make distcheck; fi