crypt_gensalt_ra: Avoid memory leak in case of crypt_gensalt_rn error

[fweimer]

This was reported by clang.

Error: CLANG_WARNING: [#def6]
libxcrypt-4.1.0/crypt.c:415:3: warning: Potential leak of memory pointed to by 'output'
#  return crypt_gensalt_rn (prefix, count, rbytes, nrbytes, output,
#  ^
libxcrypt-4.1.0/crypt.c:411:18: note: Memory is allocated
#  char *output = malloc (CRYPT_GENSALT_OUTPUT_SIZE);
#                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
libxcrypt-4.1.0/crypt.c:412:7: note: Assuming 'output' is non-null
#  if (!output)
#      ^~~~~~~
libxcrypt-4.1.0/crypt.c:412:3: note: Taking false branch
#  if (!output)
#  ^
libxcrypt-4.1.0/crypt.c:415:3: note: Potential leak of memory pointed to by 'output'
#  return crypt_gensalt_rn (prefix, count, rbytes, nrbytes, output,
#  ^
#  413|       return 0;
#  414|   
#  415|->   return crypt_gensalt_rn (prefix, count, rbytes, nrbytes, output,
#  416|                              CRYPT_GENSALT_OUTPUT_SIZE);
#  417|   }

[codecov-io]

Codecov Report

Merging #19 into develop will increase coverage by <.01%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           develop      #19      +/-   ##
===========================================
+ Coverage    97.07%   97.07%   +<.01%     
===========================================
  Files           22       22              
  Lines         1949     1952       +3     
===========================================
+ Hits          1892     1895       +3     
  Misses          57       57

Impacted Files	Coverage Δ
crypt.c	95% <100%> (+0.12%)	⬆️

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[zackw]

Nice catch! Merged.