title: installation of package ‘jpeg’ had non-zero exit status
body: <p>I am trying to install the <code>ggmap</code> package in R, but the dependency package <code>jpeg</code> has this error: </p>
  
  <pre><code>&gt; install.packages('ggmap')
  also installing the dependency ‘jpeg’
  
  
    There is a binary version available but the source version is later:
       binary  source needs_compilation
  jpeg  0.1-8 0.1-8.1              TRUE
  
  Do you want to install from sources the package which needs compilation? (Yes/no/cancel) yes
  trying URL 'https://cran.rstudio.com/bin/macosx/el-capitan/contrib/3.6/ggmap_3.0.0.tgz'
  Content type 'application/x-gzip' length 4698880 bytes (4.5 MB)
  ==================================================
  downloaded 4.5 MB
  
  
  The downloaded binary packages are in
      /var/folders/s1/r6h4z6p93731tv7xgdlv55t40000gn/T//RtmpfHHPTi/downloaded_packages
  installing the source package ‘jpeg’
  
  trying URL 'https://cran.rstudio.com/src/contrib/jpeg_0.1-8.1.tar.gz'
  Content type 'application/x-gzip' length 18116 bytes (17 KB)
  ==================================================
  downloaded 17 KB
  
  * installing *source* package ‘jpeg’ ...
  ** package ‘jpeg’ successfully unpacked and MD5 sums checked
  ** using staged installation
  ** libs
  clang -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -I/usr/local/include  -fPIC  -Wall -g -O2  -c read.c -o read.o
  clang: warning: no such sysroot directory: '/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk' [-Wmissing-sysroot]
  In file included from read.c:1:
  ./rjcommon.h:7:10: fatal error: 'stdio.h' file not found
  #include &lt;stdio.h&gt;
           ^~~~~~~~~
  1 error generated.
  make: *** [read.o] Error 1
  ERROR: compilation failed for package ‘jpeg’
  * removing ‘/Library/Frameworks/R.framework/Versions/3.6/Resources/library/jpeg’
  Warning in install.packages :
    installation of package ‘jpeg’ had non-zero exit status
  
  The downloaded source packages are in
      ‘/private/var/folders/s1/r6h4z6p93731tv7xgdlv55t40000gn/T/RtmpfHHPTi/downloaded_packages’
  </code></pre>
  
  <p>My R is updated, I'm using R 3.6.1 for Mac.</p>
  
  <p>I have tried updating <code>rlang</code>, it is version 0.4.0.</p>
  
  <p>Are there any solutions for this, or alternative packages that can be used to download google maps directly into R Markdown? Thanks in advance. </p>