Add libraw: library for processing raw image files

Let's keep jasper disabled for now, as it produces build errors:

    /mnt/Lavoro/mxe/mxe/usr/x86_64-w64-mingw32.shared/include/jasper/jas_math.h:
    In function 'bool jas_safe_intfast32_mul(int_fast32_t, int_fast32_t,
                                             int_fast32_t*)':
    /mnt/Lavoro/mxe/mxe/usr/x86_64-w64-mingw32.shared/include/jasper/jas_math.h:241:12:
    error: 'INT_FAST32_MAX' was not declared in this scope
        if (x > INT_FAST32_MAX / y) {
                        ^

It's not a required dependency, but we might want to add it later if
someone asks for it (and can provide a solution).

src/libraw-test.cpp

@@ -0,0 +1,18 @@
+/*
+ * This file is part of MXE. See LICENSE.md for licensing information.
+ */
+
+#include <iostream>
+#include <libraw.h>
+
+int main(int argc, char *argv[])
+{
+    (void)argc;
+    (void)argv;
+
+    LibRaw libRaw;
+    std::cout << "This is libraw version " << libRaw.version() << std::endl;
+    std::cout << libRaw.cameraCount() << " cameras supported." << std::endl;
+
+    return 0;
+}

src/libraw.mk

@@ -0,0 +1,31 @@
+# This file is part of MXE. See LICENSE.md for licensing information.
+
+PKG             := libraw
+$(PKG)_WEBSITE  := https://libraw.org
+$(PKG)_DESCR    := A library for reading RAW files obtained from digital photo cameras
+$(PKG)_VERSION  := 0.19.5
+$(PKG)_CHECKSUM := 9a2a40418e4fb0ab908f6d384ff6f9075f4431f8e3d79a0e44e5a6ea9e75abdc
+$(PKG)_GH_CONF  := LibRaw/LibRaw/releases
+$(PKG)_DEPS     := cc jasper jpeg lcms
+
+define $(PKG)_BUILD
+    cd '$(SOURCE_DIR)' && autoreconf -fi
+    cd '$(BUILD_DIR)' && '$(SOURCE_DIR)'/configure \
+        $(MXE_CONFIGURE_OPTS) \
+        --enable-jasper \
+        --enable-jpeg \
+        --enable-lcms \
+        --disable-examples \
+        CXXFLAGS='-std=gnu++11 $(if $(BUILD_SHARED),-DLIBRAW_BUILDLIB,-DLIBRAW_NODLL)' \
+        LDFLAGS='-lws2_32'
+    $(MAKE) -C '$(BUILD_DIR)' -j '$(JOBS)' install
+    # add missing entries to pkg-config file
+    (echo ''; \
+     echo 'Libs.private: -lws2_32 -ljasper'; \
+     echo 'Cflags.private: -DLIBRAW_NODLL';) \
+     >> '$(PREFIX)/$(TARGET)/lib/pkgconfig/$(PKG).pc'
+
+    '$(TARGET)-g++' -Wall -Wextra -std=c++11 \
+        '$(TEST_FILE)' -o '$(PREFIX)/$(TARGET)/bin/test-$(PKG).exe' \
+        `'$(TARGET)-pkg-config' libraw --cflags --libs`
+endef